toolbar上的按钮对数据记录的操作问题

阿泰，我设计了一条toolbar，设置了几个按钮，分别取记录的“第一条、下一条、上一条、最后一条”，对应的代码是：
Private Sub Toolbar1_ButtonClick(ByVal Button As MSComctlLib.Button)
Dim rs As New ADODB.Recordset
Dim cn As New ADODB.Connection
Dim sqlstr As String
Dim sqlstr1 As String
sqlstr = "select * from detailtb1"
cn.ConnectionString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" & App.Path & "\mfdatabase.mdb;Persist Security Info=False"
cn.CursorLocation = adUseClient
cn.Open
rs.CursorLocation = adUseClient
rs.Open sqlstr, cn, adOpenDynamic, adLockOptimistic
Select Case Button.Key
Case "key1"
Previewfrm.Show
Case "key3"
rs.AddNew
rs!Item = Combo1.Text
rs!NO = txtNO.Text
rs!LOTNO = txtLOTNO.Text
rs!TestBF = txtBF.Text
rs!TestAF = txtAF.Text
rs!TestChgRate = CSng(Replace(txtchg.Text, "%", "")) / 100
rs.Update
MsgBox "信息保存成功，請進行下一步操作!", vbOKOnly
Case "key4"
If Not rs.EOF Then
rs.MoveNext
Else
rs.MoveFirst
End If
Call Viewdata
Case "key6"
rs.MoveFirst
Call Viewdata
Case "key5"
rs.MovePrevious
Call Viewdata
Case "key7"
rs.MoveLast
Call Viewdata
End Select
End Sub
只有按“第一条”时有效，其他无效。我知道原因是每按一次指针都指向第一条，但不知用什么方法来避免这种情况，请阿泰指教!