Error In C# Code (mysql Database Connection)

i bind a dropdownlist to a database and later on, on button click i connect to database to get some value in a label. My 1st part works fine but when i try to do the second part i get the error message as

at System.Data.SqlClient.SqlConnection.OnError(SqlException exception, Boolean breakConnection) at System.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, Boolean breakConnection) at System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning(TdsParserStateObject stateObj) at System.Data.SqlClient.TdsParser.Run(RunBehavior runBehavior, SqlCommand cmdHandler, SqlDataReader dataStream, BulkCopySimpleResultSet bulkCopyHandler, TdsParserStateObject stateObj) at System.Data.SqlClient.SqlDataReader.ConsumeMetaData() at System.Data.SqlClient.SqlDataReader.get_MetaData() at System.Data.SqlClient.SqlCommand.FinishExecuteReader(SqlDataReader ds, RunBehavior runBehavior, String resetOptionsString) at System.Data.SqlClient.SqlCommand.RunExecuteReaderTds(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, Boolean async) at System.Data.SqlClient.SqlCommand.RunExecuteReader(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, String method, DbAsyncResult result) at System.Data.SqlClient.SqlCommand.RunExecuteReader(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, String method) at System.Data.SqlClient.SqlCommand.ExecuteReader(CommandBehavior behavior, String method) at System.Data.SqlClient.SqlCommand.ExecuteReader() at _Default.Button1_Click(Object sender, EventArgs e) in c:Documents and SettingsaMy DocumentsVisual Studio 2008WebSitesoolbar1Default.aspx.cs:line 56

My code is:

using System;
using System.Configuration;
using System.Data;
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;
using System.Data.SqlClient;
public partial class _Default : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
try
{
SqlConnection myConn = new SqlConnection("Server=localhost;Database=testcase;Integrated Security=SSPI");
SqlCommand myCmd = new SqlCommand("select skey,casecode from casetype", myConn);
myConn.Open();
SqlDataReader myReader = myCmd.ExecuteReader();
//Set up the data binding.
DropDownList3.DataSource = myReader;
DropDownList3.DataTextField = "skey";
DropDownList3.DataValueField = "casecode";
DropDownList3.DataBind();
//Close the connection.
//myConn.Close();
//myReader.Close();
//Add the item at the first position.
DropDownList3.Items.Insert(0, "<-- Select -->");
}
catch (Exception ex)
{
Response.Write(ex.StackTrace);
}
}
}
protected void Button1_Click(object sender, EventArgs e)
{
try
{
SqlConnection myConn1 = new SqlConnection("Server=localhost;Database=testcase;Integrated Security=SSPI");
SqlCommand myCmd1 = new SqlCommand("select casename,skey from casetype where skey=?", myConn1);
myConn1.Open();
SqlDataReader myReader1 = myCmd1.ExecuteReader();
String type = DropDownList3.SelectedItem.Text;
myCmd1.Parameters.AddWithValue("?", type);
}
catch (Exception exw)
{
Response.Write(exw.StackTrace);
}
}
}