Clear Unbound Text box used as input parameter to query

I've looked at everything I can find, tried all the suggestions but still
can't get this to work. I have a form that opens blank. You input your
parameter into an unbound text box then press a command button that performs
a requery of the database and returns the results in a continuous form. When
the results are returned, the parameter is listed as part of the detail in
the form so I want the parameter box to be cleared out and ready for the next
one.

My command on the Search button looks like this:

Private Sub SearchEPICode_Click()

Me.Requery

End Sub

I've tried adding Me!InputEPI = Null but nothing works. Am I adding it to
the wrong place.