You are using form control references to provide criteria to the query? Then on a copy of the query, test hard coded values for everything and see what you get using criteria that you are sure should work. If you get no results, there is likely something wrong with your join(s) or the basic query itself. In these situations, it's often best to start with the minimum (even if that's one table) and individually test criteria portions on each table as separate queries before joining the the tables in one. Test as you go.
If that approach doesn't work, posting your sql might help, but it's often difficult to pinpoint the problem without understanding the data or relationships,
The more we hear silence, the more we begin to think about our value in this universe.
Paraphrase of Professor Brian Cox.