Edit窗口Dlookup数据出来后保存出错

如下图，Dlookup写在数据来源属性里，如下图

在窗口时可以出来数据，如下图：

但保存时却报错，如下图：

回到代码时显示的是“rst.Update”这行代码是**的，如下图：

具体代码如下：

Private Sub btnSave_Click()
   ' On Error GoTo ErrorHandler
    Dim strWhere      As String
    Dim strSQL        As String
    Dim cnn           As Object 'ADODB.Connection
    Dim rst           As Object 'ADODB.Recordset
    Dim rstTmp        As Object 'DAO.Recordset
    Dim blnTransBegin As Boolean


    If Not CheckRequired(Me) Then Exit Sub
    If Not CheckTextLength(Me) Then Exit Sub
    If Not CheckRequired(Me.sfrDetail) Then Exit Sub


    Set cnn = CurrentProject.Connection


    cnn.BeginTrans: blnTransBegin = True


    strSQL = "SELECT * FROM [tblwfssdh] WHERE [WFSSBM]=" & SQLText(Me![WFSSBM])
    Set rst = OpenADORecordset(strSQL, adLockOptimistic, cnn)
    If rst.EOF Then
        rst.AddNew
        rst![WFSSBM] = GetAutoNumber("外发消数编码")
    End If
    rst![SSZLDHDATA] = Me![SSZLDHDATA]
    rst.Update
    Me![WFSSBM] = rst![WFSSBM]
    rst.Close


    strSQL = "SELECT * FROM [tblwfss] WHERE [WFSSBM]=" & SQLText(Me![WFSSBM])
    Set rst = OpenADORecordset(strSQL, adLockOptimistic, cnn)
    Do Until rst.EOF
        rst.Delete
        rst.MoveNext
    Loop
    Set rstTmp = CurrentDb.OpenRecordset("TMP_tblwfss")
    Do Until rstTmp.EOF
        rst.AddNew
        rst![WFSSBM] = Me![WFSSBM]
        rst![SCDBM] = rstTmp![SCDBM]
        rst![CPBM] = rstTmp![CPBM] 'DLookup("[CPBM]", "tblwfscdmx", "SCDBM = '" & [SCDBM] & "'") ' rstTmp![CPBM]'
        rst![GS] = rstTmp![GS] 'DLookup("[GS]", "tblwfscdmx", "SCDBM='" & [SCDBM] & "'") ' rstTmp![GS]'
        rst![CPMC] = rstTmp![CPMC] 'DLookup("[CPMC]", "tblwfscdmx", "SCDBM='" & [SCDBM] & "'") ' rstTmp![CPMC]'
        rst![SSSHDBM] = rstTmp![SSSHDBM]
        rst![SSSHSL] = rstTmp![SSSHSL]
        rst![SSSHGBP] = rstTmp![SSSHGBP]
        rst![SSSHDATE] = rstTmp![SSSHDATE]
        rst![SSBZ] = rstTmp![SSBZ]
        rst![SSSF1] = rstTmp![SSSF1]
        rst![SSSF2] = rstTmp![SSSF2]
        rst![SSSF3] = rstTmp![SSSF3]
        rst![SSSF4] = rstTmp![SSSF4]
        rst![SSSF5] = rstTmp![SSSF5]
        rst![SSBY1] = rstTmp![SSBY1]
        rst![SSBY2] = rstTmp![SSBY2]
        rst![SSBY3] = rstTmp![SSBY3]
        rst![SSBY4] = rstTmp![SSBY4]
        rst![SSBY5] = rstTmp![SSBY5]
        rst![SSZLDATE] = rstTmp![SSZLDATE]
        rst.Update
        rstTmp.MoveNext
    Loop
     rst.Close
     rstTmp.Close
     cnn.CommitTrans: blnTransBegin = False


     Form_frmwfssdh.RefreshDataList
     MsgBoxEx LoadString("Saved Successfully."), vbInformation


'    If Me.DataEntry Then
'        ClearControlValues Me
'        CurrentDb.Execute "DELETE FROM [TMP_tblwfss]"
'        Me.sfrDetail.Requery
'    Else
'        DoCmd.Close acForm, Me.Name, acSaveNo
'    End If


ExitHere:
    Set rst = Nothing
    Set cnn = Nothing
    Set rstTmp = Nothing
    Exit Sub


ErrorHandler:
    If blnTransBegin Then
        cnn.RollbackTrans
        blnTransBegin = False
    End If
    RDPErrorHandler Me.Name & ": Sub btnSave_Click()"
    Resume ExitHere
End Sub

请问要怎么改，才可以成功保存？？？