How to configure approval hierarchy base on amount?

In Document Approval, How can I configure approval hierarchy based on different range of amount?. In approval User Setup, I have used the field ‘Purchse Amount Approval Limit’ for a particular approver ID. If the amount is greater than the limit, the particular request should automatically send to next level of Approver. Now it is niether sent to next level approver or current approver.

Kindly help on this issue…