for a couple of days now. I don't know arrays at all, nor the SUMPRODUCT function, so straight away I am limited in what help I can give.

But some questions for you;

1] What are Q2 and T2? Are they particular conditions that must be met?

2] Why is the contents of the first bracket, (F1:F6=Q2), minus? I mean the minus sign before the brackets. Same question for (G1:G6=T2).

3] What is the (H1:H6) doing? It has a comma before it, but no arithmetic sign

Have you tried error checking the formula? There is an option in one of the menus for stepping through formulas which helps track through and find errors, but for the life of me I can't remember which it is.

Other than all that, the formula appears correctly formed, and so I am stumped too. I found a short explanation of SumProduct below, which may be useful;
http://www.meadinkent.co.uk/xlsumproduct.htm

Mark