missing parameter values during run-time in crystal report

Question

Hi to all,

       In ASP.NET C# language, displaying crystal report on button click and passing from date and to date (in textbox) as parameters in crystal report, finally the report processing successfully. But only the hindrance was after processing the report, when am trying to zoom, error occurs - MISSING PARAMETER VALUES (during run-time), also when clicking export, print option in toolbar.

       Herewith, I have attached my program file. kindly let me know the solution as soon as possible.

Thanks in advance.....
Nithya Dhamodaran.