Multi-level group by clause is not allowed in subquery

[blakey]

Hi

I am using access 97 and have a query the groups some fields, averages others and has a inner select to another table that sums rrequired field. I am consistently calculating averages etc for monthly periods and then annualised averages.

When I create the report any fields in the footer give rise to the error msg
multi-level group by clause is not allowed in a subquery.

I have used dsum(....) to get around the problem but can anyone tell me what causes this msg and how can it be avoided.

thanks
Bernard