The following formula is returning a #N/A error and I have no idea why. The
data and formatting of the table array and lookup values is the same. I've
tried it in both SUM and SUM(IF... variants (both array) with no luck.

Columns A & B have repeating values (table array); Columns C & D contain the
unique values of the A & B range (lookup values). The formulas in Column E
are supposed to return the count of unique loc/code within the A:B range.

Here's the range and formulas (ranges in formulas are longer than what's
depicted below).

A1 LOCATION B1 CODE C1 LOC D1
CODE E1
A2 123 MAIN STREET B2 12345 C2 123 MAIN STREET D2 12345 (formula)
A3 123 MAIN STREET B3 12345 C3 234 APPLE AVE D3 12345 (formula)
A4 234 APPLE AVE B4 12345

Both formulas:
{=SUM(($A$2:$A$18691=$C2)*($B$2:$B$18691=$D2))}
{=SUM(IF($A$2:$A$18691=$C2,IF($B$2:$B$18691=$D2,1, 0),0))}

I appreciate your help.
EU