Not thoughts, but guesses.
1. Your manifest doesn't have a Class-Path entry.
2. It doesn't have a line-ending (CR/LF) at the end of the entry it does have.
3. The entry doesn't have the right name for the jar file.
4. It doesn't have the right relative path to the jar file.
5. You used backslashes instead of slashes in the relative path.
6. You forgot to rename the zip file to have the .jar extension.
7. The jar file doesn't contain the DB2 driver.
8. The jar file doesn't contain the classes for DB2 licencing.
I'm sure there's more possibilities...
