添加字段老加不上，附代码，请指点！

<P>老是提示加入字段错误！为什么呀？</P>
<P>Public Function addFld(strName As String, strType As String) As Boolean
 On Error GoTo errHand
 Dim cmdAdo As New ADODB.Command
 Dim cmdStr As String
 addFld = True
 Dim fldDB As String
 
 fldDB = "D:\Data\World"
 'Set curlyr = Formmain.Map1.Layers(curIndex)
 Formmain.Map1.Layers.Remove curIndex
 Formmain.Map1.Refresh
 
 With cmdAdo
    .ActiveConnection = "Driver={Microsoft Visual FoxPro Driver};UID=;SourceDB=" ; fldDB ; ";SourceType=DBF;Exclusive=No;BackgroundFetch=Yes;Collate=Machine;Null=Yes;Deleted=Yes;"
    .CommandType = adCmdText
       cmdStr = "alter table country  add   " ; strName ; " moString "
    .CommandText = cmdStr
    .Execute
  End With
 
 'SetupLayers
  Dim curlyr As New MapObjects2.MapLayer
  Dim curDc As New DataConnection
  Dim curGS As GeoDataset
  curDc.Database = fldDB
  Set curGS = curDc.FindGeoDataset("country")
  curlyr.GeoDataset = curGS
  Formmain.Map1.Layers.Add curlyr
  curlyr.Tag = curDc.Database
  Formmain.Map1.Layers.MoveTo 0, curIndex
  Formmain.Map1.Refresh
  
    Exit Function
  
errHand:
  MsgBox "加入字段有误", vbExclamation + vbOKOnly, "系统提示"
  addFld = False
End Function</P>
<P>Private Sub CmdAddfld_Click()
If boolNull = False Then Exit Sub
  If addFld(txtFldName.text, moString) = False Then
    SetupLayers
    Exit Sub
 End If</P>
<P>End Sub</P>
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<img src="images/post/smile/dvbbs/em02.gif" />帮帮忙呀！

只读属性？

<P>关注中</P><img src="images/post/smile/dvbbs/em01.gif" />

只读属性，只有通过其他修改DBF的方式修改字段