Hello,
Is the error captured in MII tracer or in NW log? If latter - I'd recommend to check your custom code:
com.atos.serviceext.OrderReleaseServiceExt.execute(OrderReleaseServiceExt.java:51)
com.atos.serviceext.OrderReleaseServiceExt.execute(OrderReleaseServiceExt.java:34)
com.sap.me.activity.impl.ActivityExecutionService.execute(ActivityExecutionService.java:92)
Though it's weird it doesn't show actual exception.
Regards,
Konstantin