=SUMPRODUCT(--(Sheet1!$A$2:$A$20=Sheet2!$A2),--(Sheet1!C$2:C$20<""))

--
HTH

Bob

(there's no email, no snail mail, but somewhere should be gmail in my addy)

"Carol" wrote in message
...
Hi

Can anyone advise which excel function should I use to return the desired
results? i.e. to count the no. of times e.g. computer components appear in
the month of Apr?

I am using a interactive worksheet i.e. if I changes the month to e.g. Jun
in worksheet 2, the count should also changes.

I tried countif and counta but it is not the desired result I am looking
at
cos when the month changes in worksheet 2, the count is not updated.

Example
Worksheet 1
Product cat Product Apr May
Jun......
Computer components Mouse 5 10
Computer software Windows 97 4
Computer components Keyboard 5

Worksheet 2
Product cat Apr
Computer components 2
Computer software 1

Thanks