Whether you use a prompt or reference to textbox, the same parameter has to be under each date field on separate criteria rows as I originally described.
Why does the unbound textbox require a date value? Does it have formatting that requires a date and not just a number?
If you want the query results to show on form make the query the RecordSource for the form. Review this tutorial to see one way to build filter into a form: http://datapigtechnologies.com/flash...tomfilter.html
At this point, I don't think I will be able to help unless you provide the project so I can see what you have done. Make copy, remove confidential data, run Compact & Repair, zip if large, attach to post or upload to fileshare site such as box.com and post link.