上杉达也对浅仓南:cmdupdate

我用VB+ACCESS编程时候，用到update会有这句错误的话提示？
“当前记录不支持更新。这可能是提供程序的限制，也可能是选定锁定类型的限制。”
程序如下:
Private Sub cmdUpdate_Click()
'更新所添加或者修改的记录
On Error GoTo errHandler:
Dim str As String
str = txtname.Text
With DataEnv.rsstudent
.Fields("name") = txtname.Text
.Fields("model") = txtmodel.Text
.Fields("id") = txtid.Text
.Fields("dknow") = txtdknow.Text
' .Fields("birthday") = dtpBirth.Value
' .Fields("tel") = txtTelephone.Text
.Fields("address") = txtaddress.Text
.Fields("buytype") = txtbuytype.Text
' If mstrFileName <> "" Then Call WriteImage(.Fields("photo"), mstrFileName)
.Update
End With
cmdReport.Caption = "报表(&R)"
cmdUpdate.Enabled = False
fraInfo.Enabled = False
mbClose = True
If DataEnv.rssqlSeek.State = adStateClosed Then DataEnv.rssqlSeek.Open
'刷新右端用以导航的网格控件
Call RefreshGrid
'根据记录集中记录的个数，改变各个按钮的状态
Call ChangeBrowseState
'定位到刚刚添加或者修改过的记录
DataEnv.rssqlSeek.MoveFirst
DataEnv.rssqlSeek.Find "name='" & str & "'"
fraSeek.Enabled = True
fraBrowse.Enabled = True
grdScan.Enabled = True
Exit Sub
errHandler:
MsgBox Err.Description, vbCritical, " 错误"
End Sub
''当改变记录集时，需要刷新用户导航的网格控件
Sub RefreshGrid()
grdScan.DataMember = ""
grdScan.Refresh
DataEnv.rssqlSeek.Requery
grdScan.DataMember = "sqlSeek"
grdScan.Refresh

'刷新各个绑定控件
Call grdScan_Change
End Sub