What does your STP error log show? Look in Object Spawner and Object Spawner console logs as well.
For me, it usually boils down to the permission issue (ID executing STP could it write to the log files?)
You may log on to your SAS EVM portal and ensure that APM shows initialized AND enabled. (SAS EVM > Browse > Services (chart view is better) and select on APM or ACM).
Your STP configured to run under STP or workspace server?
Your STP runs under sassrv or an equivalent ID?
What is the group membership of sassrv ID?
Are you running any STP and not specific APM based report?
You may also enable STP debugging on the fly; http://support.sas.com/kb/12/571.html
G'Luck.