Why do jobs stop ?

Hello,
we sometimes have problems with some UBE submitted from the Web Client, that stop after a few moments, without any explanation. Maybe it is a coïncidence, but it started consecutively to our migration from V6R1 to V7R1.
We just have this message in joblog :
Message . . . . : Job 170087/JDE08/MYUBE was ended by user ONEWORLD.
Cause . . . . . : User ONEWORLD issued an immediate end job request for job 170087/JDE08/MYUBE.

Any idea of what could cause this ?
ERP 8.XE SP24 (OS400 V7R1)

Did you verify you have the E1 required PTF list for V7R1?

See the IBM document for details.
II14493 - ORACLE WORLD AND ENTERPRISEONE SUPPORT REQUIRED PTF LIST FOR V7R1M0