Problem with function for count with criteria

Hi,

I would really appreciate if someone helped me with getting a function/formula for counting number of occurrences in a worksheet.

My requirement is to count the number of times an event occurs in a column (say) B, provided another event occurs in column (say) A. However if another event occurs in column (say) C, then count for B for that particular row need not be counted.

I discovered this problem when I had to make counts for individual coumns B & C with the same condition met in A using array function of SUM for two criteria. However certain events occurred both in B & C for which i want only one count (as once in B or C) and not two counts (as once in B & once in C.). Basically I want the count to be shown only in B without it being counted in C.

I hope this is not too confusing...and somebody might be able to help.

Thank you.