How to pass parameters in sap crystal reports & VS2010

Hi,  

How to pass parameters in sap crystal reports & VS2010.

I passed parameter like below

1. Report.SetParameterValue("ExpiryDate", Convert.ToDateTime(Session["ExpiryDate"].ToString()));

 or

2. ParameterDiscreteValue paramDV = new ParameterDiscreteValue();

                paramDV.Value =Convert.ToDateTime(Session["ExpiryDate"]);

                NPR.ParameterFields["@ExpiryDate"].CurrentValues.Clear();

                NPR.ParameterFields["@ExpiryDate"].DefaultValues.Clear();

                NPR.ParameterFields["@ExpiryDate"].CurrentValues.Add(paramDV);

but in both ways i got error(missed parameter values). Thanks,