Localhost connecting database problem

Server Error in '/WebSetup1' Application.
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Object reference not set to an instance of an object.
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.NullReferenceException: Object reference not set to an instance of an object.

Source Error:


Line 101: {
Line 102:
Line 103: rdr.Close();
Line 104:
Line 105: string script = "<script type='text/javascript'>alert('ERROR!!!!Data Not found ...........');</script>";


Source File: c:\Inetpub\wwwroot\WebSetup1\AddStudy.aspx.cs Line: 103

Stack Trace:


[NullReferenceException: Object reference not set to an instance of an object.]
AddStudy.Page_Load(Object sender, EventArgs e) in c:\Inetpub\wwwroot\WebSetup1\AddStudy.aspx.cs:103
System.Web.Util.CalliHelper.EventArgFunctionCaller(IntPtr fp, Object o, Object t, EventArgs e) +14
System.Web.Util.CalliEventHandlerDelegateProxy.Callback(Object sender, EventArgs e) +35
System.Web.UI.Control.OnLoad(EventArgs e) +99
System.Web.UI.Control.LoadRecursive() +50
System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +627




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Version Information: Microsoft .NET Framework Version:2.0.50727.3620; ASP.NET Version:2.0.50727.3618

what is rdr? clearly rdr is null. Please post full code of Page_Load

if (!IsPostBack)
{
SqlConnection connection = new SqlConnection(ConfigurationManager.ConnectionStrings["conStr"].ConnectionString);

SqlDataReader rdr = null;
SqlDataReader rdr1 = null;

try
{

SqlCommand commandToItemTable = new SqlCommand("select StudyTypeDesc from ItemTable", connection);
SqlCommand commandToItemTable1 = new SqlCommand("select * from ItemTable1", connection);
connection.Open();
rdr = commandToItemTable.ExecuteReader();

while (rdr.Read())
{
StudyTypeDescDropDownList.Items.Add(rdr.GetString(0));

}
rdr.Close();

rdr1 = commandToItemTable1.ExecuteReader();

while (rdr1.Read())
{
ModalityNameDropDownList.Items.Add(rdr1.GetString(0));

}
rdr1.Close();

}
catch(NullReferenceException)
{
rdr.Close();

string script = "<script type='text/javascript'>alert('ERROR!!!!Connection with database failed...........');</script>";
Page page = HttpContext.Current.CurrentHandler as Page;
if (!(page.ClientScript.IsClientScriptBlockRegistered("alert")))
{

page.ClientScript.RegisterClientScriptBlock(this.GetType(), "alert", script);
}
}
catch (Exception ex)
{

rdr.Close();<-------------------------------showing here error

string script = "<script type='text/javascript'>alert('ERROR!!!!Data Not found ...........');</script>";
Page page = HttpContext.Current.CurrentHandler as Page;
if (!(page.ClientScript.IsClientScriptBlockRegistered("alert")))
{

page.ClientScript.RegisterClientScriptBlock(this.GetType(), "alert", script);
}
}
finally
{

connection.Close();

}
Even i remove rdr.close() from catch block it will show that script MessageBox.. saying data Not found..