AME Standard PO - Position Hierarchy to AME

Dear SCM Gurus,

We are currenlty using Position Hierarchy, now need to move to AMe for a complex approval process.

In AME, Rule works fine while testing, but in while submitting the PO in purchaisng module, it says No approver found. What setup i should consider.

In financial option i removed teh check box use approval hierarcy

and Workflow Start Process = PO Approval Top Process

Approval Workflow = PO Approval

Regards,

Chaks