If function not working across multiple columns and multiple functions nested

Im having trouble with a function trying to get two cells to "merge"

I have 2 columns, Column D and Column G, both have either a number or #N/A in them. Column D represents package prices shipped with USPS, while Column G represents package prices shipped with FedEx. The only reason #N/A is in some of them is a lack of proper record taking. The function I have written now is as follows:

=IF(D2>0,D2,IF(G2>0,G2,x))

If does the first part fine, but when it gets to the part where I tell it to check column G, it comes up as #N/A.

Maybe this is the wrong route to take, but I'm hoping to have one column with these two columns combined so I can have a separate column next to it with what I actually charged for shipping and compare.

Any help will be greatly appreciated.

Thanks