I am having trouble with the following formula:

=SUMPRODUCT(--(RBS!A2:A9999="1/4/2008"),--(RBS!A2:A9999<="31/3/2009"),--(RBS!M2:M9999="Directors Loan"),RBS!L2:L9999)

It is giving me a "0" as the result. I know this is not the case.

Column A is the date range
Column M is the description of the item
Column L is the cost for the item

If you should have an answer to the above question please let me have it in
the above format for ease of understanding. Many thanks in advance.

Mark