Error: couldn't query the process result handle staf rc: 7

Hi  everybody,

I'm trying to run a certification test on a Workbench 3.5.7.0 and when I run the verify test ,I get a Error:

ERROR: VTAF::Framework::Core::Common::STAF::STAFProcess::STAFGetProcessOutput  couldn't query the process result handle staf rc: 7. 

I tried to reinstall the STAF, but it still don't work ,

Does anybody can help me?  thank you very much!