Activate an Open Word Document

Apologies. I have posted this question (in part) before, but have not had an answer.

I have an Excel VBA UserForm with several CommandButtons. I am using the CommandButtons to invoke a Help facility, whereby the topic numbers relate to bookmarks in a Word document. This part works OK.

I have written the following code .....

Private Sub OpenHelpDocument(strTopic)
Dim strPath As String
strPath = "C:\My Documents\Help Topics.doc"
Dim objWord As Object
Dim docWord As Object
Set objWord = CreateObject("Word.Application")
objWord.Visible = True
    If funIsDocOpen(strPath) = True Then

        MsgBox "Testing"
        Set docWord = objWord.documents.Activate(Filename:=strPath)   ' **** This code fails ***
    Else
        Set docWord = objWord.documents.Open(Filename:=strPath, ReadOnly:=True)
    End If
docWord.Bookmarks(strTopic).Range.Select
End Sub

When the sub 'OpenHelpDocument' is run for the first time, the function 'funIsDocOpen' correctly returns 'False' and the Word Document 'Help Topics.doc' opens in read-only mode at the correct bookmark. So far, so good.

However, when run for a second time with a new topic (with 'Help Topics.doc' already open), it fails "Run-time error '438': Object doesn't support this property or method". The MsgBox "Testing" is displayed prior to the error message.

I want the Word Document to remain open and available for (potentially) multiple Help/Topic/Bookmark enquiries. It will be closed later.

How can I 'Activate' the existing Open Document when the function returns 'True'? I am assuming that 'Activate' is the correct teminology!!

Thanks in anticipation, and apologies again for a repeated question.