Modifying query parameters in code

When I run the below code, it modifys the query but it puts the form criteria as the parameter and not the literal values.  How do I re-write this so the criteria for TransDate becomes Between 7/11/2011 and 7/12/2012 instead of:   Between [Forms]![F_PRINT_ACTIVITY]![t_start] And [Forms]![F_PRINT_ACTIVITY]![t_end])

Thanks

 

Set qdf = CurrentDb.QueryDefs("Q_RECEIVING_ACTIVITY_REPORT_XLT")
                ssql = "SELECT * From Q_RECEIVING_ACTIVITY_REPORT " & vbCrLf
                ssql = ssql & "WHERE(TransDate Between [Forms]![F_PRINT_ACTIVITY]![t_start] And [Forms]![F_PRINT_ACTIVITY]![t_end])"
                qdf.sql = ssql