First, I’d use our deployers rather than Ant. 🙂 But I’m assuming you’re not doing that because your project structure is somehow to “unique” for our deployers to work with it.
If you must use Ant, you need to either configure it to compile your code with full debugging information included (default is off) or don’t compile at all and just repackage the class files that Eclipse has compiled.
–Scott
MyEclipse Support