Error:SqlException ubhandled by user code

While debugging the asp.net web page the error shows :SqlException was unhandled by user code.
the source code of the page is as below:

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="executiveinfo.aspx.cs" Inherits="executiveinfo" %>

<%@ Register assembly="AjaxControlToolkit" namespace="AjaxControlToolkit" tagprefix="cc1" %>

Executive Name*
Branch Code*	01 02 03 04 05 06 07 08
Address*
City*	Kanpur Lucknow Muradabad Bareilly Hardoi Unnao Shahjahanpur Rai Bareilly
Email Id*
Gender*	RepeatDirection="Horizontal"> Male Female
Mobile no*	runat="server" Enabled="True" FilterType="Numbers" TargetControlID="txtmobileno">
Remark
	Width="135px" />

and the C# code is:


using System;
using System.Collections;
using System.Configuration;
using System.Data;
using System.Data.SqlClient;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Xml.Linq;

public partial class executiveinfo : System.Web.UI.Page
{
SqlConnection cnn = new SqlConnection(@"Integrated Security=SSPI;Persist Security Info=False;Initial Catalog=LMS;Data Source=SHESH-PC\SHESHSQLEXPRESSS");
protected void Page_Load(object sender, EventArgs e)
{

}
protected void Button1_Click(object sender, EventArgs e)
{

SqlCommand cm = new SqlCommand();
string sql = "insert into executiveinfo(executivename,branchcode,address,city,emailid,gender,mobileno,remark,entrydate)values('" + txtexecutivename.Text + "','" + ddlbranchcode.SelectedItem.ToString() + "','" + txtaddress.Text + "','" + ddlcity.SelectedItem.ToString() + "','"+txtemailid.Text+"','" +RadioButtonList1.SelectedItem.ToString() + "'," + txtmobileno.Text + ",'" + txtremark.Text + "','" + DateTime.Now.ToString() + "')";
cm.Connection = cnn;
cm.CommandType = CommandType.Text;
cm.CommandText = sql;
int a = 0;
cnn.Open();
a = cm.ExecuteNonQuery();
cnn.Close();
if (a == 0)
{
lblmsg.Text = "DATA NOT SAVED";
}
else
{

lblmsg.Text = "DATA SAVED";

}


}
}


and the error is at line 48 col 1 in the code line{cnn.Open();} and the table is dbo.executiveinfo

and schema of table is:

Column_name Type Computed Length Prec Scale
id numeric no 9 18 0
executivename varchar no 50
branchcode varchar no 30
address varchar no 50
city varchar no 50
emailid varchar no 50
gender varchar no 50
mobileno numeric no 9 18 0
remark varchar no 50
entrydate datetime no 8
activestatus bit no 1