Invoice Tolerances not working

Summary: System not placing overbilling hold.

Content (required):

Our client wants to apply holds on an invoice if the invoice amount more than $100 over the total PO amount.

To achieve this requirement, we tried to setup the invoice tolerances with type Amount Based.

PO Entered for $ 8,000.00

Invoiced $15,000.00

Since the invoice amount is more than $7000, it should go on hold but that is not happening.

Can anyone let me know if I am missing anything or is there another way to achieve this requirement(Invoice cannot exceed $100 over the total PO amount).

Amount Based Setup Which I have made, please let me know I need to make any corrections in the setup to meet my requirement.