AME for Requisition Pre-Approval Group

Dear Gurus,

I have sucessfully implemented and use AME in my testing environment (r12.1.1). I have created 2 group for pre-approval.

I use AME with position hierarchy.

Our scenario is like this :

a) require pre-approval from finance dept for all purchases.

b) if item category is IT, then require pre approval from IT dept.

What i'm not able to achieve now is,when item category is IT, i wanted to have the flow llike this;

Requester-->finance dept pre-approval-->IT Dept pre-approval--> final approver(one position up).

But instead, it behave like this

Requester-->finance dept pre-approval-->final approver(one position up)-->IT Dept pre-approval.