LS2J threw ClassNotFound error even just get "java/lang/Integer"

I’ve debugged the code, and found jSession maybe failed to initiated, because jSession is empty.

Set jSession = new JavaSession()

So whenever this code called:

Set jClass = jSession.getClass(“java/lang/Integer;”)

ClassNotFound error threw.

When I move code into an agent, it works fine.

Any advice will be highly appreciated.