vb.net操作Word中书签的问题

[myriceme]

我想对word中有书签的位置插入文本，但不知道用什么命令，以下是我的代码：

Imports Microsoft.Office.Core
Imports Microsoft.Office.Interop

Public Class Form1

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim wordApp As New Word.Application
        Dim wordDoc As New Word.Document
        wordDoc = wordApp.Documents.Open(My.Application.Info.DirectoryPath() & "\a.doc")

        If Err.Number = 462 Then
            wordApp = CreateObject("Word.Application") '建立WORD实例
            wordDoc = wordApp.Documents.Open(My.Application.Info.DirectoryPath() & "\a.doc") '打开文件并赋予文件实例
        End If

        wordDoc.Close() '关闭文档实例
        wordApp.Quit()
        wordDoc = Nothing
        wordApp = Nothing
    End Sub

[wuyq11]

If Doc.Bookmarks.Exists("a") Then
Dim b As Object = "a"
Dim bk As Word.Bookmark = Doc.Bookmarks.Item(b)
Dim [Nothing] As [Object] = System.Reflection.Missing.Value
//bk.Range.Text
Dim table As Word.Table = WordDoc.Tables.Add(bk.Range, 1, 1, [Nothing], [Nothing])
End If

[myriceme]

我的word文档中的标签是固定的就3个：
a1
b1
c1

能不能用下面这种方式来给标签处添加文本：
先GOTO到这个标签，然后用Selection.TypeText Text:="Hello"给标签处赋值，有几个标签就循环几次。

我用了如下语句可是不对：
wordApp.Selection.GoTo("wdGoToBookmark", "wdGoToNext", , "a1")
wordApp.Selection.TypeText(Text:="aaa")

wordApp.Selection.GoTo("wdGoToBookmark", "wdGoToNext", , "b1")
wordApp.Selection.TypeText(Text:="bbb")

wordApp.Selection.GoTo("wdGoToBookmark", "wdGoToNext", , "c1")
wordApp.Selection.TypeText(Text:="ccc")

谢谢。

[myriceme]

在标签处插入文本是成功了可是插入的位置却不对，代码如下：

Imports Microsoft.Office.Core
Imports Microsoft.Office.Interop
Imports Microsoft.Office.Interop.Word.WdGoToItem
Imports Microsoft.Office.Interop.Word.WdGoToDirection

Public Class Form1

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim wordApp As New Word.Application
        Dim wordDoc As New Word.Document
        'wordDoc = wordApp.Documents.Open(My.Application.Info.DirectoryPath() & "\a.doc")
        wordDoc = wordApp.Documents.Open("d:\a.doc")
        If Err.Number = 462 Then
            wordApp = CreateObject("Word.Application") '建立WORD实例
            'wordDoc = wordApp.Documents.Open(My.Application.Info.DirectoryPath() & "\a.doc") '打开文件并赋予文件实例
            wordDoc = wordApp.Documents.Open("d:\a.doc")
        End If


        'wordApp.Selection.GoTo("wdGoToBookmark", "wdGoToNext", [nothing], "a")
        wordApp.Selection.GoTo(What:=wdGoToBookmark, Which:=wdGoToAbsolute, Name:="a")
        wordApp.Selection.TypeText(Text:="Hello")
        wordApp.Selection.GoTo(What:=wdGoToBookmark, Which:=wdGoToAbsolute, Name:="b")
        wordApp.Selection.TypeText(Text:="hello")

        wordDoc.Close() '关闭文档实例
        wordApp.Quit()
        wordDoc = Nothing
        wordApp = Nothing
    End Sub
End Class

问题1：我的第一个标签“a”在word文档的第三行插入文本时却插在文档的第一行；
问题2：程序在第一个标签“a”处插入文本后运行下面一行程序时发生错误告诉我找不到第二个标签“b”；