มีปัญหากับ Access ครับ พอกระบวนการเสร็จเรียบร้อยแล้ว ไฟล์ access.ldb ค้าง ไม่ยอมหาย

Dim FileIn As New FileInfo(Server.MapPath("STD.mdb"))

                    If FileIn.Exists Then
                        FileIn.Delete()
                    End If

                    Sub_CreateNewMDB(Server.MapPath("STD.mdb"), Jet4x)


                    ' -------------------------------------------------------------------

                    Dim Cn As ADODB.Connection, Cat As ADOX.Catalog, objTable As ADOX.Table

                    Cn = New ADODB.Connection
                    Cat = New ADOX.Catalog
                    objTable = New ADOX.Table

                    Cn.Open("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" & Server.MapPath("STD.mdb"))
                    Cat.ActiveConnection = Cn

                    'เพิ่มชื่อตาราง
                    objTable.Name = "Survey"

                    'เพิ่มชื่อฟิลด์
                    objTable.Columns.Append("STUDENT_CODE") 'รหัสประจำตัวนิสิต
                    objTable.Columns.Append("STUDENT_NAME") 'ชื่อ-สกุล

                    objTable.Columns.Append("CITIZENID") 'รหัสประจำตัวประชาชน

                    objTable.Columns.Append("BAN_NUMBER") 'บ้านเลขที่
                    objTable.Columns.Append("MOO") 'หมู่
                    objTable.Columns.Append("ALLEYS") 'ซอย
                    objTable.Columns.Append("ROAD") 'ถนน
                    objTable.Columns.Append("BAN") 'บ้าน
                    objTable.Columns.Append("DISTRICT") 'ตำบล
                    objTable.Columns.Append("AMPUR") 'อำเภอ
                    objTable.Columns.Append("PROVINCE") 'จังหวัด
                    objTable.Columns.Append("POST") 'รหัสไปรษณยี์

                    objTable.Columns.Append("PHONE") 'เบอร์โทรศัพท์
                    objTable.Columns.Append("EMAIL") 'อีเมล์

                    objTable.Columns.Append("MAJOR") 'สาขา
                    objTable.Columns.Append("FACULTY") 'คณะ

                    objTable.Columns.Append("SURVEY_YEAR") 'ปีการศึกษา

                    objTable.Columns.Append("WORK_STATUS") 'สถานะการทำงาน

                    Cat.Tables.Append(objTable)


                    objTable = Nothing
                    Cat = Nothing
                    Cn.Close()
                    Cn = Nothing


                    '--------------------------------------------------------------------------

                    Dim MyConnection As New OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" & Server.MapPath("STD.mdb"))
                    MyConnection.Open()

                    Dim sql_string, Name As String

                    sql1 = " SELECT S_SURVEY.*, STUDENTMAIN.STUDENTCODE, "
                    sql1 &= " STUDENTMAIN.STUDENTNAME, STUDENTMAIN.STUDENTSURNAME, "
                    sql1 &= " PREFIXID.PREFIXNAME, STUDENTDETAIL.CITIZENID,FACULTY.FACULTYNAME, MAJOR.MAJORNAME "
                    sql1 &= " FROM S_SURVEY "
                    sql1 &= " INNER JOIN STUDENTMAIN ON STUDENTMAIN.STUDENTID = S_SURVEY.STUDENTID "
                    sql1 &= " INNER JOIN PREFIXID ON STUDENTMAIN.PREFIXID = PREFIXID.PREFIXID "
                    sql1 &= " INNER JOIN STUDENTDETAIL ON STUDENTMAIN.STUDENTID = STUDENTDETAIL.STUDENTID "
                    sql1 &= " INNER JOIN FACULTY ON STUDENTMAIN.FACULTYID = FACULTY.FACULTYID"
                    sql1 &= " INNER JOIN MAJOR ON STUDENTMAIN.MAJORID = MAJOR.MAJORID "
                    sql1 &= " where SURVEY_YEAR = '" & Me.DropDownList1.Text & "' "

                    Cmd1 = New OracleCommand(sql1, Conn)
                    dtReader1 = Cmd1.ExecuteReader()

                    While dtReader1.Read()

                        Name = dtReader1.Item("PREFIXNAME") & "" & dtReader1.Item("STUDENTNAME") & "   " & dtReader1.Item("STUDENTSURNAME")

                        sql_string = " INSERT INTO Survey "
                        sql_string &= " (STUDENT_CODE,STUDENT_NAME, "
                        sql_string &= " CITIZENID,"
                        sql_string &= " BAN_NUMBER,MOO, "
                        sql_string &= " ALLEYS,ROAD, "
                        sql_string &= " BAN,DISTRICT, "
                        sql_string &= " AMPUR,PROVINCE, "
                        sql_string &= " POST,PHONE, "
                        sql_string &= " EMAIL, "
                        sql_string &= " MAJOR, "
                        sql_string &= " FACULTY, "
                        sql_string &= " SURVEY_YEAR, "
                        sql_string &= " WORK_STATUS) "

                        sql_string &= " VALUES "

                        sql_string &= " ('" & dtReader1.Item("STUDENTCODE") & "','" & Name & "', "
                        sql_string &= " '" & dtReader1.Item("CITIZENID") & "',"
                        sql_string &= " '" & dtReader1.Item("SURVEY_NUMBER") & "','" & dtReader1.Item("SURVEY_MOO") & "', "
                        sql_string &= " '" & dtReader1.Item("SURVEY_ALLEYS") & "','" & dtReader1.Item("SURVEY_ROAD") & "', "
                        sql_string &= " '" & dtReader1.Item("SURVEY_HOME") & "','" & dtReader1.Item("SURVEY_DISTRICT") & "', "
                        sql_string &= " '" & dtReader1.Item("SURVEY_ZONE") & "','" & dtReader1.Item("SURVEY_PROVINCE") & "', "
                        sql_string &= " '" & dtReader1.Item("SURVEY_POSTALCODE") & "','" & dtReader1.Item("SURVEY_PHONE") & "', "
                        sql_string &= " '" & dtReader1.Item("SURVEY_EMAIL") & "', "

                        sql_string &= " '" & dtReader1.Item("MAJORNAME") & "', "
                        sql_string &= " '" & dtReader1.Item("FACULTYNAME") & "', "

                        sql_string &= " '" & dtReader1.Item("SURVEY_YEAR") & "', "

                        sql_string &= " '" & dtReader1.Item("SURVEY_CHECK_WORK") & "')"


                        Dim MyCommand As New OleDbCommand(sql_string, MyConnection)
                        MyCommand.ExecuteNonQuery()

                    End While



                    dtReader.Close()

                    dtReader1.Close()

                    Cn.Close()

                    MyConnection.Close()