JAVA Compiler error : class file has wrong version 49.0, should be 48.0

Compiler error message :

    [javac] class file has wrong version 49.0, should be 48.0
    [javac] Please remove or make sure it appears in the correct subdirectory of the classpath.
    [javac] import com.common.dao.QueueDAO;
    [javac]                         ^
    [javac] 1 error

Reason :

Java 1.4 creates class files labeled with version 48.0
Java 1.5 creates class files labeled with version 49.0
Check the java compiler versions


Related links :
http://forums.sun.com/thread.jspa?threadID=644158
http://www.dreamincode.net/forums/showtopic49155.htm