There is an issue in Silk Performer 2011 where ‘Real-Time measures’ can cause Silk Performer not to end the test after simulation time. This can occur regardless of the length of the test, amount of users or number of agents.  

The issue has been resolved with SP83_HF7.zip for SilkPerformer 2011, or else you can disable ‘Real-Time measures’ when running a test.