InDesignBookmarks

I am writhing below code for adding bookmarks in InDesign CS4

BMNd.Texts(1).Select()

Dim hd2 As InDesign.HyperlinkTextDestination

Dim hdd2 As InDesign.HyperlinkTextDestinations = IndDoc.HyperlinkTextDestinations

Dim indTD2 As InDesign.Text = BMNd.Texts(1)

hd2 = hdd2.Add(indTD2)

Dim BkName As String = indTD2.Contents

BkName = RemoveJunk(BkName)

hd2.Name = BkName

myBookmark2 = myBookmark.Bookmarks.Add(hd2)

But it is giving Exception as Name is already used

but in my InDesign document there is no any bookmark present

some times it is working fine

please help me