Dispute in Approved-Pending Completion status in Advanced Collection 11i

1.  We are raising a dispute through Advanced Collections 11i (It uses AR Credit Memo work flow)

2.  The dispute is sent for approval to Supervisor. 

3. The dispute gets approved by the Supervisor.

4. But it Times Out.......and the status of the dispute is "Approved - Pending completion" Status in the History Tab.

5. When we see the Workflow, It shows that After approval it timed out.

What is the possible reasons for this Dispute getting timed out. And while going in Approved Status, It is going in "Approved - Pending COmpletion Status"?

Thanks