Can Any One tell Actually What this Error?

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data.SqlClient;
using System.Data;

namespace JobPortal
{
public partial class view_jobseekers_byarea : System.Web.UI.Page
{
SqlConnection con = null;
SqlDataAdapter adp = null;
string expyrs, mnth;
int areaid;
string connstring=@"";
protected void Page_Load(object sender, EventArgs e)
{

}



protected void btnsearch_Click(object sender, EventArgs e)
{
expyrs = ddlexpyrs.Text;
mnth = ddlmnth.Text;
areaid = ddlarea.SelectedValue;

}

public void area()
{
con = new SqlConnection(connstring);//@"Data Source=.\SQLEXPRESS;AttachDbFilename=E:\PRJ\JobPortal\JobPortal\App_Data\JobportalDB.mdf;Integrated Security=True;User Instance=True");
con.Open();

string query = "";
adp = new SqlDataAdapter(query, con);
DataSet ds = new DataSet();
adp.Fill(ds);

ddlarea.DataSource = ds.Tables[0];
ddlarea.DataTextField = "area_name";
ddlarea.DataValueField = "area_id";
ddlarea.DataBind();
ddlarea.Items.Insert(0, new ListItem("select", "0"));

con.Close();
}
protected void Button4_Click(object sender, EventArgs e)
{
Multiview1.SetActiveView(view2);
}

protected void ddlarea_SelectedIndexChanged(object sender, EventArgs e)
{
area();
}

protected void GridView1_RowCommand(object sender, GridViewCommandEventArgs e)
{
if(e.CommandName.Equals("select"))
{
GridView gvr = (GridView)GridView1.NamingContainer.;

}



}

protected void GridView1_SelectedIndexChanged(object sender, EventArgs e)
{
try
{
GridView1.SelectedIndex = e.NewSelectedIndex;
foreach (GridViewRow gr in GridView1.Rows)
{
if (gr.RowIndex == GridView1.SelectedIndex)
{
recruiter.JobID = gr.Cells[1].Text;
recruiter.OrgName = gr.Cells[2].Text;
Response.Redirect("~/JobSeeker/SearchJobs/frmFullSelectedJobDetail.aspx?JobId=" + recruiter.JobID + "&OrgName=" + recruiter.OrgName);
}
}
}
catch (Exception)
{

throw;
}



}
}
}