I am trying to look at the cell to my left, and if it is PROD, then look at the ranges on the US sheet and INTL sheet and bring the answer forward from the 3rd column. It worked when I had just one range but when I added the second range I get NA and FALSE. Is it correct to use a plus sign between the two ranges? Thank you!

=IF(D5="PROD",VLOOKUP($A5,US!A4:F5+INTL!A4:F5,3,0))