No Approver Found for PO

Hello there

We are using Position Hierarchy and we are facing No Approver Found for PO.

The Hierarchy is 1. PO Preparer

                         2. 1st PO Approver

                         3. Final Approver

This "No approver found for this PO" comes after 2 seconds the Final approver approved the PO from the notification.

I have checked all these setups and everything is OKAY

Approval Group,

Positions

Approval Assignment,

The Position hierarchy,

Document Type,

Employee,

user and

run the "Fill Employee Hierarchy"

Please help

Thank you

Meron