Tax Amount Not Displayed In Purchase Order

Dear Experts,

1) i have created purchase request through MRP 

2) then i go to Purchase Order select Vendor and then Copy From Purchase Request

3) then i put Quantity, Price, Tax code all works fine but Tax Amount is not Displayed.

issue only when Purchase Request through MRP.

i am using SAP 9.0 PL 7 and also tried in SAP 9.1 PL 0 but issue is same

please find Snap

Thanks & Regards

Navanath

then Go to Purchase Order Copy From Purchase Request