update后 mdb数据库不变，datagrideview2显示已经变了

如下代码，我用da.update 更新mdb数据库，数据库内容却没变，但是datagrideview显示变了。运行没有报错。不知道哪里出错了。
请大家指导一下，谢谢！

Private Sub sequencePlan()
Dim cn As OleDbConnection
Dim da As OleDbDataAdapter
Dim ds As DataSet = New DataSet
'On Error Resume Next


Dim cnStr As String = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=tmpDB.mdb; Persist Security Info=False"
cn = New OleDbConnection(cnStr)
cn.Open()

Dim strSql As String = "select * from DATAIO_PLAN order by Equipment ASC, SMT_TIME asc, DT DESC"

da = New OleDbDataAdapter(strSql, cn)

Dim Mybuilder As OleDbCommandBuilder = New OleDbCommandBuilder(da)
da.Fill(ds, "A")
da.FillSchema(ds, System.Data.SchemaType.Mapped)
datagrideview2.DataSource = ds.Tables("A")

cn.Close()


Dim Irow As Integer = ds.Tables("A").Rows.Count

Dim I1 As Integer
Dim lastTime As Date
Dim currentTime As Date
Dim calcTime As Date

Dim YN As Boolean = True '判定是否是倒数第一个（设备号）
Dim IsSameEquip As Boolean = True
Dim DTStr As Integer = 0
Dim EquipStr As String = ds.Tables("A").Rows(Irow - 1).Item(6).ToString()
Dim EquipStrCurrent As String

For I1 = Irow - 1 To 0 Step -1
EquipStrCurrent = ds.Tables("A").Rows(I1).Item(6).ToString()
currentTime = Format(CDate(ds.Tables("A").Rows(I1).Item(13).ToString()), "yyyy-MM-dd HH:mm")

DTStr = CInt(ds.Tables("A").Rows(I1).Item(12).ToString())

If EquipStrCurrent = EquipStr Then
IsSameEquip = True
If YN = False Then
Dim DTStrTemp As Integer = (DTStr / OE) + changeOverTime
calcTime = DateAdd("S", -DTStrTemp, lastTime)

If calcTime > currentTime Then
lastTime = currentTime
Else
calcTime = DateAdd("S", -DTStrTemp, lastTime)
ds.Tables("A").Rows(I1).BeginEdit()
ds.Tables("A").Rows(I1)("DATAIOTIME") = calcTime ' Format(calcTime, "yyyy-MM-dd HH:mm") '修改一行
ds.Tables("A").Rows(I1).EndEdit()
ds.AcceptChanges()

lastTime = calcTime
End If
Else
lastTime = currentTime
End If

YN = False
Else
IsSameEquip = False
EquipStr = ds.Tables("A").Rows(I1).Item(6).ToString()
lastTime = currentTime
YN = True
End If

Next

da.Update(ds, "A") '须将结果传回数据源时打开连接，update

da.Dispose()
ds.Dispose()


End Sub