Using CR 8.5
Reporting from SQL 2003

I am creating (trying to) a report that uses parameters to display technical data. Although there is this problem that i cant seem to shake. I have two fields that contain serial numbers that need to be queried. I can create a parameter that searches one table although i can't create one that searches both at the same time.
Is there a way i can reference both tables as one? Or any other suggestions that can make this query possible?
Let me know i require more detail..

Thanks for your time