利用JPA的annotation能不能调用oracle中的函数？

在oracle10g中写了一个function，利用

@NamedNativeQuery(name = "addUser", query = "{call addUser(:pPortalID,:ploginid,:ploginpasswd,:pSelfQuiz,:pSelfAnswer,:pUserEmail)}", hints = { @QueryHint(name = "org.hibernate.callable", value = "true") }, resultClass = User.class)

来调用函数addUser，但是在运行时总是提示：

javax.persistence.PersistenceException: org.hibernate.exception.SQLGrammarException: could not execute query
	at org.hibernate.ejb.AbstractEntityManagerImpl.throwPersistenceException(AbstractEntityManagerImpl.java:630)
	at org.hibernate.ejb.QueryImpl.getSingleResult(QueryImpl.java:108)
	at com.igrs.sso.dao.impl.UserDAOImpl.addUser(UserDAOImpl.java:59)
	at com.igrs.sso.service.impl.UserServiceImpl.addUser(UserServiceImpl.java:41)
	at com.igrs.sso.page.SignupForm.submit(SignupForm.java:172)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
	at java.lang.reflect.Method.invoke(Method.java:597)
	at org.apache.tapestry.listener.ListenerMethodInvokerImpl.invokeTargetMethod(ListenerMethodInvokerImpl.java:276)
	at org.apache.tapestry.listener.ListenerMethodInvokerImpl.invokeListenerMethod(ListenerMethodInvokerImpl.java:221)
	at org.apache.tapestry.listener.ListenerMethodInvokerImpl.searchAndInvoke(ListenerMethodInvokerImpl.java:157)
	at org.apache.tapestry.listener.ListenerMethodInvokerImpl.invokeListenerMethod(ListenerMethodInvokerImpl.java:80)
	at org.apache.tapestry.listener.SyntheticListener.actionTriggered(SyntheticListener.java:52)
	at org.apache.tapestry.binding.ListenerMethodBinding.actionTriggered(ListenerMethodBinding.java:77)
	at org.apache.tapestry.listener.ListenerInvokerTerminator.invokeListener(ListenerInvokerTerminator.java:50)
	at $ListenerInvoker_115a65efa94.invokeListener($ListenerInvoker_115a65efa94.java)
	at $ListenerInvoker_115a65efa93.invokeListener($ListenerInvoker_115a65efa93.java)
	at org.apache.tapestry.form.Form.renderComponent(Form.java:200)
	at org.apache.tapestry.AbstractComponent.render(AbstractComponent.java:725)
	at org.apache.tapestry.services.impl.DefaultResponseBuilder.render(DefaultResponseBuilder.java:180)
	at org.apache.tapestry.form.Form.rewind(Form.java:269)
	at org.apache.tapestry.engine.RequestCycle.rewindForm(RequestCycle.java:453)
	at org.apache.tapestry.form.Form.trigger(Form.java:280)
	at org.apache.tapestry.engine.DirectService.triggerComponent(DirectService.java:166)
	at org.apache.tapestry.engine.DirectService.service(DirectService.java:142)
	at $IEngineService_115a65efb0c.service($IEngineService_115a65efb0c.java)
	at org.apache.tapestry.services.impl.EngineServiceOuterProxy.service(EngineServiceOuterProxy.java:72)
	at org.apache.tapestry.engine.AbstractEngine.service(AbstractEngine.java:237)
	at org.apache.tapestry.services.impl.InvokeEngineTerminator.service(InvokeEngineTerminator.java:54)
	at $WebRequestServicer_115a65efad7.service($WebRequestServicer_115a65efad7.java)
	at $WebRequestServicer_115a65efad3.service($WebRequestServicer_115a65efad3.java)
	at org.apache.tapestry.services.impl.WebRequestServicerPipelineBridge.service(WebRequestServicerPipelineBridge.java:61)
	at $ServletRequestServicer_115a65efac5.service($ServletRequestServicer_115a65efac5.java)
	at org.apache.tapestry.request.DecodedRequestInjector.service(DecodedRequestInjector.java:55)
	at $ServletRequestServicerFilter_115a65efac1.service($ServletRequestServicerFilter_115a65efac1.java)
	at $ServletRequestServicer_115a65efac7.service($ServletRequestServicer_115a65efac7.java)
	at org.apache.tapestry.multipart.MultipartDecoderFilter.service(MultipartDecoderFilter.java:52)
	at $ServletRequestServicerFilter_115a65efabf.service($ServletRequestServicerFilter_115a65efabf.java)
	at $ServletRequestServicer_115a65efac7.service($ServletRequestServicer_115a65efac7.java)
	at org.apache.tapestry.services.impl.SetupRequestEncoding.service(SetupRequestEncoding.java:53)
	at $ServletRequestServicerFilter_115a65efac3.service($ServletRequestServicerFilter_115a65efac3.java)
	at $ServletRequestServicer_115a65efac7.service($ServletRequestServicer_115a65efac7.java)
	at $ServletRequestServicer_115a65efab9.service($ServletRequestServicer_115a65efab9.java)
	at org.apache.tapestry.ApplicationServlet.doService(ApplicationServlet.java:126)
	at org.apache.tapestry.ApplicationServlet.doPost(ApplicationServlet.java:171)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:710)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128)
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:263)
	at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:844)
	at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:584)
	at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:447)
	at java.lang.Thread.run(Thread.java:619)
Caused by: org.hibernate.exception.SQLGrammarException: could not execute query
	at org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:67)
	at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:43)
	at org.hibernate.loader.Loader.doList(Loader.java:2223)
	at org.hibernate.loader.Loader.listIgnoreQueryCache(Loader.java:2104)
	at org.hibernate.loader.Loader.list(Loader.java:2099)
	at org.hibernate.loader.custom.CustomLoader.list(CustomLoader.java:289)
	at org.hibernate.impl.SessionImpl.listCustomQuery(SessionImpl.java:1695)
	at org.hibernate.impl.AbstractSessionImpl.list(AbstractSessionImpl.java:142)
	at org.hibernate.impl.SQLQueryImpl.list(SQLQueryImpl.java:152)
	at org.hibernate.ejb.QueryImpl.getSingleResult(QueryImpl.java:82)
	... 58 more
Caused by: java.sql.SQLException: ORA-06550: line 1, column 7:
PLS-00221: 'ADDUSER' is not a procedure or is undefined
ORA-06550: line 1, column 7:
PL/SQL: Statement ignored

	at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:112)
	at oracle.jdbc.driver.T4CTTIoer.processError(T4CTTIoer.java:331)
	at oracle.jdbc.driver.T4CTTIoer.processError(T4CTTIoer.java:288)
	at oracle.jdbc.driver.T4C8Oall.receive(T4C8Oall.java:743)
	at oracle.jdbc.driver.T4CCallableStatement.doOall8(T4CCallableStatement.java:215)
	at oracle.jdbc.driver.T4CCallableStatement.executeForRows(T4CCallableStatement.java:954)
	at oracle.jdbc.driver.OracleStatement.doExecuteWithTimeout(OracleStatement.java:1168)
	at oracle.jdbc.driver.OraclePreparedStatement.executeInternal(OraclePreparedStatement.java:3285)
	at oracle.jdbc.driver.OraclePreparedStatement.execute(OraclePreparedStatement.java:3390)
	at oracle.jdbc.driver.OracleCallableStatement.execute(OracleCallableStatement.java:4223)
	at org.apache.tomcat.dbcp.dbcp.DelegatingPreparedStatement.execute(DelegatingPreparedStatement.java:169)
	at org.hibernate.dialect.MySQLDialect.getResultSet(MySQLDialect.java:316)
	at org.hibernate.jdbc.AbstractBatcher.getResultSet(AbstractBatcher.java:193)
	at org.hibernate.loader.Loader.getResultSet(Loader.java:1784)
	at org.hibernate.loader.Loader.doQuery(Loader.java:674)
	at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:236)
	at org.hibernate.loader.Loader.doList(Loader.java:2220)
	... 65 more

，请问这是怎么回事？难道只能调用存储过程而不能调用函数吗？