cbo to pass report criteria variable to report, need help on IF statement

I have 3 cbos: Employee Name, Report Type and Report Instance.

The user selects the Employee Name then the Report Type (this cbo is
populated through a SQL Union Select query run after selecting Employee
Name) then they select the Report Instance (populated through a SQL
Union Select query based on Report Type). The user then clicks a button
that prints the selected report instance, i.e. John Doe --> Performance
Report --> 10/10/06.

Problem is, the Report instance will be one of two data types: Text or
Date.
I currently have the Report Instance cbo data formatted as a date when
it is cited in the strlinkcriteria line but this does not work if the
data is text. How can I correct this? Is there a better way?

Thanks!!!!