Getting a java.lang.NoClassDefFoundError on one build, but not the other using the exact same jar

This is a bit of an odd problem, but I'm kind of desperate because I'm all out of ideas and google has reached it's end.

I have to builds on two separate machines going. They both use the same jar (pulled from the same location). Problem is, one is getting a java.lang.NoClassDefFoundError where the other is not.

Pretty much the only reasons I can see this happening is if the classpath is incorrect, problem is they both have the same.

the specific classes it can't find are:

java.lang.NoClassDefFoundError: org/apache/commons/lang/time/StopWatch
..
java.lang.NoClassDefFoundError: org/apache/velocity/context/Context
...
Caused by: java.lang.ClassNotFoundException: org.apache.velocity.context.Context

Sorry, can't post the whole stacktrace for securiy reasons, but just trying to figu开发者_JAVA百科re this out. Just looking for any other reasons this could be happening if someone has run into it.

Thanks