I do have the following in code behind:

cmd = New SqlCommand("SELECT UserName FROM ............... sql go here ....", con)
                cmd.Parameters.AddWithValue("@IDAutoNumber", AutoNumber)
                con.Open()
                reader = cmd.ExecuteReader()
                cmd.Parameters.Clear()

                If reader.HasRows Then
                    While reader.Read()

                        'Here we get UserName from each record read
                        NewReadUserName = CType(reader("UserName"), Object).ToString

                        'Here we update table for particular UserName
                        cmd = New SqlCommand("UPDATE RegistrationList .............sql go here .........", con)
                        cmd.Parameters.AddWithValue("@AutoNumber", AutoNumber)
                        cmd.Parameters.AddWithValue("@NewReadUserName", NewReadUserName)
                        If NumberOfRecordsFound = 1 Then
                            cmd.Parameters.AddWithValue("@WordToEnter", "Found one")
                        ElseIf NumberOfRecordsFound > 1 Then
                            cmd.Parameters.AddWithValue("@WordToEnter", "Found more than one")
                        End If
                        cmd.ExecuteNonQuery()
                        cmd.Parameters.Clear()

                    End While

                End If

                reader.Close()
                con.Close()

I'm receiving this message when I try to access the page: 

Server Error in '/' Application.

There is already an open DataReader associated with this Command which must be closed first.

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.InvalidOperationException: There is already an open DataReader associated with this Command which must be closed first.

Source Error: 

Line 164:                            cmd.Parameters.AddWithValue("@WordToEnterForFirstPlace", "TieFirstPlaceWinner")
Line 165:                        End IfLine 166:                        cmd.ExecuteNonQuery()Line 167:                        cmd.Parameters.Clear()
Line 168:

Source File: C:\bGlocal\TalentShow\AdminShowsVotingResultPage.aspx    Line: 166 

Stack Trace: 

[InvalidOperationException: There is already an open DataReader associated with this Command which must be closed first.]
   System.Data.SqlClient.SqlInternalConnectionTds.ValidateConnectionForExecute(SqlCommand command) +1543253
   System.Data.SqlClient.SqlConnection.ValidateConnectionForExecute(String method, SqlCommand command) +101
   System.Data.SqlClient.SqlCommand.ValidateCommand(String method, Boolean async) +268
   System.Data.SqlClient.SqlCommand.InternalExecuteNonQuery(TaskCompletionSource`1 completion, String methodName, Boolean sendToPipe, Int32 timeout, Boolean asyncWrite) +96
   System.Data.SqlClient.SqlCommand.ExecuteNonQuery() +192
   ASP.talentshow_adminshowsvotingresultpage_aspx.Page_Load(Object sender, EventArgs e) in C:\bGlocal\TalentShow\AdminShowsVotingResultPage.aspx:166
   System.Web.Util.CalliEventHandlerDelegateProxy.Callback(Object sender, EventArgs e) +51
   System.Web.UI.Control.OnLoad(EventArgs e) +95
   System.Web.UI.Control.LoadRecursive() +59
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +2952

I can not close the reader before it start reading. What should I do here?

Thanks to all.