ant编译报错“xxx does not exist”

Compiling 3 source files to E:\WorkSpace\util\build
    [javac] E:\WorkSpace\util\src\java\com\util\DateFormatter.java:14: package org.joda.time does not exist
    [javac] import org.joda.time.DateTime;

cannot find symbol
    [javac] symbol  : class DateTime
    [javac] location: class com.spokesoft.util.DateFormatter
    [javac]         DateTime dt = new DateTime(localDate.getTime());

工程里面buildPath都配置正常，但是ant编译时候报错，可以检查ant配置文件用echo返回加入的包的位置，看看是否已经争取引用。