Supervisor Heirarchy : Approval setup

Hi Team

I want to setup below approval functionlaity.

We are using "Supervisor Heiracrchy"

I want to setup below approval functionlaity.

1) If PO < 1000 THEN BUYER ( A) SHOULD himself should APPROVE THE PO.
2) If PO Values falls between 1000 to 2000 then "B" should approve the PO . ( B is supervisor of "A")
3) If PO value is above 2000 then "C" should approve the PO . ( "C" is supervisor of "B")

Now for the first two points 1 and 2 above , its working fine but when i create a PO with more than 2000 then also it goes to "B" and gets approved.
I tried changing the "document forward method" to "DIRECT  but it did not worked .