Error:SqlConnection Does Not Support Parallel Transactions

This is my code in vb.net with Sql transaction
I am using insertcommand and update command for executing the sqlquery
in consecutive transactions as follows.
How can I achive parallel transactions in sql
------------------start of code---------------------
try
bID = Convert.ToInt32(Session("batchID"))
                    strSQL = ""
                    strSQL = "Insert into sessiondelayed (batchid,ActualEndDate) values (" & bID & ",'" & Format(d1, "MM/dd/yyyy") & "')"

                    sqlCon = New System.Data.SqlClient.SqlConnection(ConfigurationSettings.AppSettings("conString"))


                    Dim s1 As String = sqlCon.ConnectionString.ToString
                    sqlDaEndDate = New System.Data.SqlClient.SqlDataAdapter("Select * from sessiondelayed", sqlCon)
                    dsEndDate = New DataSet
                    sqlDaEndDate.Fill(dsEndDate)

                    dbcommandBuilder = New SqlClient.SqlCommandBuilder(sqlDaEndDate)

                    'sqlCon.BeginTransaction()
                    'sqlDaEndDate.InsertCommand.Transaction = tr
                    If sqlCon.State = ConnectionState.Closed Then
                        sqlCon.Open()
                    End If
                    sqlDaEndDate.InsertCommand = sqlCon.CreateCommand()
                    tr = sqlCon.BeginTransaction(IsolationLevel.ReadCommitted)
                    sqlDaEndDate.InsertCommand.Connection = sqlCon
                    sqlDaEndDate.InsertCommand.Transaction = tr
                    sqlDaEndDate.InsertCommand.CommandText = strSQL
                    sqlDaEndDate.InsertCommand.CommandType = CommandType.Text


                    sqlDaEndDate.InsertCommand.ExecuteNonQuery()
                    tr.Commit()
                    sqlDaEndDate.Update(dsEndDate)
                    sqlCon.Close()
                End If
            Catch es As Exception


                Dim s2 As String = es.Message
                If sqlCon.State = ConnectionState.Closed Then
                    sqlCon.Open()
                End If
                strSQL = " update SessionDelayed set ActualEndDate= '" & Format(d1, "MM/dd/yyyy") & "' where batchid=" & bID & ""
                sqlDaEndDate.UpdateCommand = sqlCon.CreateCommand()
                tr1 = sqlCon.BeginTransaction(IsolationLevel.ReadCommitted)
                sqlDaEndDate.UpdateCommand.Connection = sqlCon
                sqlDaEndDate.UpdateCommand.Transaction = tr1
                sqlDaEndDate.UpdateCommand.CommandText = strSQL
                sqlDaEndDate.UpdateCommand.CommandType = CommandType.Text
                sqlDaEndDate.UpdateCommand.ExecuteNonQuery()
                tr1.Commit()
                sqlDaEndDate.Update(dsEndDate)
                sqlCon.Close()

 

            End Try

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