Openfire im gateway plugins install

If you install im gateway plugin firstly, perhaps you did not encounter this problem.
If you upgrade your im gateway plugin, perhaps you have been in trouble.
Unfortunately,I encountered this problem some days ago.
I used the openfire 3.4.5, and it contains the gateway plugins;
now,I want to upgrade to openfire3.5.2, of course the gateway plugin should be upgraded correspondingly.
so I do the following: removed gateway.jar (old) and added gateway.jar(version 1.2.3a).
I restarted the openfire,the gateway page existsed in the Admin Console, but the Setting is not available.
I suspected that there is the issue about DWR compitibility in openfire plugins, but I can not find the solution.
More strangely, log error: java. lang. ClassNotFoundException: org. jivesoftware. openfire. gateway. util. Log4JToOpenfireAppender
I have no idea,so google, baidu and www.igniterealtime.org
some one say it need delete the old gateway plugin completely; so I remembered the database.
I removed all table about gateway in database, and all properties about gateway in the table named jiveproperties.
restart,
great.
So far so good ,I have solved the problem.