Nina:
Are you setting up a query by form? That is, using a form to allow the user to set the query criteria?
If so, I think the the problem may be that the query is not referencing the controls on your form. (Apologies if you've already tried this.)
The solution is to open the query in design view, right click on the criteria cell for the field to be filtered and select Build. From the Expression Builder, identify the form where the criteria are set, find the specific control/s and use them with the appropriate operators to set up the criteria string.
When the report is opened it will open the query which, in turn, will look at the form for the criteria.
Let me know if this helps or isn't what you were looking for.
Good luck.
Larry De Laruelle
larry1de@yahoo.com