VB.net程序关闭后后台还在与SQL连接

这段是批量将Excel数据写入数据库的，但是关闭程序后程序怎么还会在后台运行的？是连接没关闭吗？

        For ii = 0 To ListBox1.Items.Count - 1            fileName = ListBox1.Items.Item(ii)            Dim ExcelConnection As New System.Data.OleDb.OleDbConnection("Provider=Microsoft.ACE.OLEDB.12.0; Data Source='" & fileName & "'; Extended Properties=""Excel 12.0 Xml; HDR=Yes""")            ExcelConnection.Open()            Dim expr As String = "SELECT [PASS_ID] FROM [拆分明细$]"            Dim objCmdSelect As OleDbCommand = New OleDbCommand(expr, ExcelConnection)            Dim objDR As OleDbDataReader            Dim SQLconn As New SqlConnection()            Dim ConnString As String = "server=localhost;database=STdata;user id=sa;password=Nngs8888!"            SQLconn.ConnectionString = ConnString            SQLconn.Open()            Using bulkCopy As New SqlBulkCopy(SQLconn)                bulkCopy.DestinationTableName = "chaifen"                Try                    objDR = objCmdSelect.ExecuteReader                    bulkCopy.WriteToServer(objDR)                    SQLconn.Close()                Catch ex As Exception                    MsgBox(ex.ToString)                End Try            End Using            ExcelConnection.Close()            ProgressBar1.Value = ii        Next