If cell X has any value then enter value from cell Y but not if cell X is a negative value

Hi there!

I've run into a road block in my excel spreadsheet.

The end game is to roughly calculate postage costs for 2,500 orders.

But to get there I need to assign postage costs to a column but only if the transaction required postage.

Some of these transactions are refunds or the payment wasn't approved so then postage wouldn't apply.

I think I've almost figured it out except my formula assigns postage costs to refunds too. Refunds can be seen as negative values in the "Amount $" column.

My excel spreadsheet already has these formulas:

D2
=IF(ISNUMBER(SEARCH("Transaction Approved",C2)),B2,"")
D3
=IF(ISNUMBER(SEARCH("Transaction Approved",C3)),B3,"")
ETC.

E2
=IF(D2="",,$G$2)
E3
=IF(D3="",,$G$2)
ETC.

I have also attached the excel file.

Postage for orders.xlsx

Possibly,
=IF(D2="","",IF(D2<0,"",$G$2))