Can't Get Package Installation To Work Properly...

I'm using a SL5500 with Sharp 3.10 ROM, and developing a Java app which I hope to release generally when it's ready. It's a Sudoku helper (it doesn't solve them, just lets you do them on screen): it's called Zudoku.

I have a very preliminary version working, and I've been trying to package and install it. The file Zudoku.class will run happily from my development directory, so if I do:

cd /home/zaurus/Programming/Java
evm Zudoku

things happen as they should.

I've built an ipkg following the instructions on the Java FAQ on the ZUG pages. The run_Zudoku file at this stage reads:

cd /home/QtPalmtop/java/
evm -XappName=run_Zudoku Zudoku

...and the Zudoku.class file is in /home/QtPalmtop/java. Everything seems to be in the right places, but when I tap the icon, the program doesn't run.

If I use the console, navigate to /home/QtPalmtop/bin, and do ./run_Zudoku, I get an error message:

Exception in thread "main", java.lang.NoClassDefFoundError: Sudoku at Zudoku.main (bytecode 0)

However, exactly the same class file, run from my development directory, runs without any problems. If I change the run_Zudoku file so that it cd's to /home/zaurus/Programming/Java instead of the QtPalmtop directory, it runs the program, provides the icon on the taskbar - no problems!

What am I missing?