=SUMPRODUCT(('Wk (1)'!F1:F10000="BPS")*('Wk (1)'!P1:P10000="BPS=General Enquiries/Operator;")*('Wk (1)'!I1:I10000))
Is this an existing value in the column?

If you count the occurences of BPS and General enquiries like this:

=SUMPRODUCT(('Wk (1)'!F1:F10000="BPS")*('Wk (1)'!P1:P10000="BPS=General Enquiries/Operator;"))

do you get an error, too??