ASP.NET

protected void Page_Load(object sender, EventArgs e)
{
    try
    {
        string snam = Session["na"].ToString();
        chi_id = Convert.ToInt32(Request.QueryString["c_id"]);
        get_names();
        //SqlConnection con = new SqlConnection("Server=.; Database=eclsc; Trusted_Connection=yes");
        SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings["newcon"].ConnectionString);
        SqlCommand cmd = new SqlCommand();
        cmd.Connection = con;
        cmd.CommandText = "select product_id, image,price,sh_desc,case when stock_on_hand >0 then 'In Stock' else convert(nvarchar, stock_on_hand) end from " + snam + "  where child_id=@child_id";
        cmd.Parameters.Add("@child_id", SqlDbType.Int).Value = chi_id;
        SqlDataAdapter sda = new SqlDataAdapter(cmd);
        DataTable dt = new DataTable();
        con.Open();
        sda.Fill(dt);
        DataView dview = dt.DefaultView;
        DataList1.DataSource = dview;
        DataList1.DataBind();
        con.Close();
    }
    catch(SqlException se)
    {
        ErrHandler.WriteError(se.Message);
    }
    catch(Exception ee)
    {
        ErrHandler.WriteError(ee.Message);
    }
}

<br />
 Description: The application attempted to perform an operation not allowed by the security policy.  To grant this application the required permission please contact your system administrator or change the application's trust level in the configuration file.<br />
<br />
 Exception Details: System.Security.SecurityException: Request for the permission of type 'System.Security.Permissions.FileIOPermission, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' failed.<br />
<br />
Source Error:<br />
<br />
An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.<br />
<br />