The situation is this:

On tab 1 I have columns [A] Month, [b] Cost, [D] Amount

On Tab 2 I have columns [A] Cost, [B-M] Month 1, 2, 3, 4 etc.

On Tab 2 I have listed the cost types and want to total them going across by
month.

So I want add the costs on Tab 1 column [D], when the cost [A] and month [b]
on Tab 2 equals that on Tab 1 [b] and [A] respectively.

I have tried the below Sumif and Sumproduct as array formulas but neither
gives the correct answer.

{=SUMIF('Variable'!$D$429:$D$599,AND($A51='Variabl e'!$B$429:$B$599,TEXT(B$2,"mmmm-yy")='Variable'!$A$429:$A$599))}

{=SUMPRODUCT((AND($A51='Variable'!$B$429:$B$599,B$ 2='Variable'!$A$429:$A$599))*('Variable'!$D$429:$D $599))}

Any help would be appreciated.

Thanks
Rick