The reason my formulas didn't work is because you changed the start point of the lookup array in the MATCH function. If you leave the start point on row 1, then it would have been fine. If starting in row 1 isn't possible, then you'll need to add a correction factor to that part of the formula like this:

for cell E3, use:
=IF(ISNA(MATCH(C3 & D3,A3:A12 & B3:B12,0)),"",ADDRESS(MATCH(C3 & D3,A3:A12 & B3:B12,0)+(ROW(A3)-1),COLUMN(A3),1,1))
with Ctrl-Shift-Enter


for cell F3, use:
=IF(ISNA(MATCH(C3 & D3,A3:A12 & B3:B12,0)),"",ADDRESS(MATCH(C3 & D3,A3:A12 & B3:B12,0)+(ROW(B3)-1),COLUMN(B3),1,1))
with Ctrl-Shift-Enter

These formulas are now corrected for pairs that don't match the list.

Cheers,