problem with button click event codes

this is button click code

protected void Button1_Click1(object sender, EventArgs e)//login as website member
{
RequiredFieldValidator1.Enabled = true;
RequiredFieldValidator2.Enabled = true;
RequiredFieldValidator3.Enabled = true;
RegularExpressionValidator1.Enabled = true;
if (IsPostBack)
{
if (TextBox3.Text == Label7.Text)
{
string constring = "server=localhost;database=SanjeshOrganizationDB;Trusted_connection=true";
SqlConnection con0 = new SqlConnection(constring);
con0.Open();
SqlCommand com0 = new SqlCommand("select Username from Profile_Information where Username='" + TextBox1.Text + "' and Password='" + TextBox2.Text + "'", con0);
SqlDataReader rdr = com0.ExecuteReader();
try
{
if (rdr.HasRows)
{
rdr.Close();
Session["Username"] = com0.ExecuteScalar();
System.Threading.Thread.Sleep(TimeSpan.FromSeconds(3));
Label8.Text = "wait...";
System.Threading.Thread.Sleep(TimeSpan.FromSeconds(3));
Label8.ForeColor = System.Drawing.Color.Green;
Response.Redirect("MainPage.aspx");
con0.Close();

}
else
{
HyperLink1.Visible = true;
Label8.Text = "incorrect username and password";
}
}
catch
{
HyperLink1.Visible = true;
Label8.Text = "error ";
}
}
else
{
Label8.Text = "incorrect capcha code";
}
}
}

sorry you right.