Why this code is not running.This is Showing error in con.Open();

<%@Import Namespace="System.Data"%>
<%@Import Namespace="System.Data.SqlClient"%>
<%@Page Language="C#" Debug="true" %>
<script  runat="server" language="c#">
void Page_Load(object sender,EventArgs e)
{
if (!IsPostBack)
{
BindGridview();
}
}
void BindGridview()
{
SqlConnection con = new SqlConnection("Data Source=JDPANDEY-PC;Integrated Security=true;Initial Catalog=GridViewTesting");
con.Open();
SqlCommand cmd = new SqlCommand("select * from User", con);
SqlDataAdapter da = new SqlDataAdapter(cmd);
con.Close();        
DataSet ds = new DataSet();
da.Fill(ds);
gvrecords.DataSource = ds;
gvrecords.DataBind();
}