SQL Server Error: Incorrect syntax near datadownload

Hi all,

       i have generated one application using asp.net with c#.

the concept is,

when i click button , the data has been display excell sheet. but in my application its gettting few errors  like "incorrect syntax near datadownload" . using stored procedure am retreiveing the data from database, please give me a solution for this app..

my code is:

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.IO;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Data.SqlClient;


public partial class _Default : System.Web.UI.Page 
{
    string s = ConfigurationManager.AppSettings["const"].ToString();
    protected void Page_Load(object sender, EventArgs e)
    {

    }
    private DataTable Getdata(SqlCommand cmd)
    {
        DataTable dt = new DataTable();
        
        SqlConnection con = new SqlConnection(s);
        SqlDataAdapter da = new SqlDataAdapter();
        cmd.CommandType = CommandType.Text;
        cmd.Connection = con;
        try
        {
            con.Open();
            da.SelectCommand = cmd;
            da.Fill(dt);
            return dt;
        }
        catch (Exception ex)
        {
            throw ex;
        }
        finally
        {
            con.Close();
            da.Dispose();
            con.Dispose();

        }
    }
    protected void download_Click(object sender, EventArgs e)
    {
       
            SqlConnection con = new SqlConnection(s);
            SqlCommand cmd = new SqlCommand("datadownload", con);
            cmd.CommandType = CommandType.StoredProcedure;
            cmd.Parameters.AddWithValue("@Destinations", SqlDbType.VarChar);
           
            if (con.State == ConnectionState.Closed)
            {
                con.Open();
                cmd.ExecuteNonQuery();

            }
            con.Close();
          
       

        DataTable dt = Getdata(cmd);

        GridView gv1 = new GridView();
        gv1.AllowPaging = false;
        gv1.DataSource = dt;
        gv1.DataBind();

        Response.Clear();
        Response.Buffer = true;
        Response.AddHeader("content-disposition", "attachment;filename=GridViewExport.xls");
        Response.Charset = "";
        Response.ContentType = "application/vnd.ms-excel";
        StringWriter sw = new StringWriter();
        HtmlTextWriter hw = new HtmlTextWriter(sw);

        for (int i = 0; i < gv1.Rows.Count; i++)
        {
            gv1.Rows[i].Attributes.Add("class", "textmode");

        }
        gv1.RenderControl(hw);
        string style = @"<style> .textmode { mso-number-format:\@; } </style>";
        Response.Write(style);
        Response.Output.Write(sw.ToString());
        Response.Flush();
        Response.End();

    }
}


thanks to all...