1. Set a breakpoint in the producer espace.
2. Tell the producer espace to "Debug in Public Area"
3. Tell the consumer espace to "Debug in Public Area"
4. Set the Entry eSpace, on consumer, by going to Debugger -> Select Entry eSpace
5. Do actions that should cause the breakpoint to be hit.

http://www.outsystems.com/forums/discussion/9314/debugging-across-espaces-does-not-always-work/