主题：不保存退出窗口问题

Dim dt As DataTable=Tables("kpinfo").DataTable
Dim dt1 As DataTable=Tables("ldinfo").DataTable
If dt.haschanges And dt1.haschanges Then
    If MessageBox.Show("是否保存当前单据?","提示",MessageBoxButtons.YesNo,MessageBoxIcon.Information)=7 Then '如果按否则删掉本行数据
        For Each dr As DataRow In dt.DataRows
            For Each dr1 As DataRow In dt1.DataRows               
                If dr1.RowState=DataRowstate.added And dr.RowState=DataRowstate.added  Then
                    dr.delete
                    dr1.delete
                End If
            Next
        Next     
    Else '否则退回编辑界面
        MessageBox.Show("请点击保存按钮保存","提示",MessageBoxButtons.OK,MessageBoxIcon.Information)
        Return
    End If
End If

e.Form.close
Forms("windows").open

上述代码，为什么实现不了当提示是否保存，选择否时，删除“kpinfo”和“ldinfo”新增行，只会删除“ldinfo”表中的新增行。

敬请各位大师帮我看一下！谢谢了

Dim dt As DataTable=Tables("kpinfo").DataTable
Dim dt1 As DataTable=Tables("ldinfo").DataTable
If dt.haschanges And dt1.haschanges Then
    If MessageBox.Show("是否保存当前单据?","提示",MessageBoxButtons.YesNo,MessageBoxIcon.Information)=7 Then '如果按否则删掉本行数据
        For i As Integer = dt.datarows.count - 1 To 0 Step -1
            If dt.datarows(i).RowState=DataRowstate.added Then
                dt.datarows(i).delete
            End If
        Next
        For i As Integer = dt1.datarows.count - 1 To 0 Step -1
            If dt1.datarows(i).RowState=DataRowstate.added Then
                dt1.datarows(i).delete
            End If
        Next
    Else '否则退回编辑界面
        MessageBox.Show("请点击保存按钮保存","提示",MessageBoxButtons.OK,MessageBoxIcon.Information)
        Return
    End If
End If

e.Form.close
Forms("windows").open