>>>According to the description of the case I got, the stored procedure generated just a single row with 0 in quantity and in the sum_cost columns.
>>
>>OK, that's a bit clearer now. So the data into the report is a one row cursor with zero in both columns but the report is showing a value greater than 0 for one of the columns. Is that right?
>
>Yes.

Any calculations on the report field? If you add in another field and set its value to the same as the field showing the incorrect value, what happens?

If the value is from a variable, check if the variable depends on some other variable. Make sure there is no funny calculation on the variable.

That's all I can think of at the moment