using stored procedures in asp.net

[sofia_khan]

hi,
i have a stored procedure named as'usp_rp_era_rejected_claims_detail'.

ALTER PROCEDURE [dbo].[usp_rp_era_rejected_claims_detail] 
( 
@S_Nos varchar (max)=null, 
@Practice_Code varchar(500)=null, 
@Date_From varchar(10)=null, 
@Date_To varchar(10)=null, 
@Date_Type char(1)=null, --'E' for Entry Date , 'C' Check Date 
@Report_Type char(1)=null --'U' unresolved, 'R' resolved 
) 
AS 
BEGIN 

DECLARE @SQL Nvarchar(4000);

I have an form in asp.net.The form has a dropdown for Practice_Code,2 txtboxes for Date_From,Date_To respectively and radio buttons for Date_Type and Report_Type.When i click the Refresh button,the data should b shown in a grid.
i m using 3 layered architecture.In bussiness layer i have used the following code:

public void GetClaims(string strSno,string strPracticecode,string strDatefrom,string strDateto,string strDatetype,string strReporttype)
{
DbAccess helper = new DbAccess();
using (var db = helper.getDBContext())
{
var GetClaims = (from Claims in db.usp_rp_era_rejected_claims_detail(strSno,strPracticecode,strDatefrom,strDateto,Convert.ToChar(strDatetype),Convert.ToChar(strReporttype)) select Claims);


}
}

and in event handler,i have used the following coding:

protected void btnRefresh_Click(object sender, EventArgs e)
{

var Claims = objRejectedandResolvedClaims.GetClaims(null,ddlPractice.SelectedValue.ToString(),txtFrom.Text,txtTo.Text,rdoCheckdate.Text.ToString(),rdoResolved.Text.ToString()).ToList();


if (Claims.ToString().Length > 0)
{

gvDetail.DataSource = null;
gvDetail.DataSource = Claims;
gvDetail.DataBind();
}
}

But errors are there.Plz help me.Its urgent....
Regards....