Opening Word Document with VBA - Run Time Error '438'

Hi there.

I am trying to open a word document and insert text from Excel into the bookmarks. However, I am receiving the error '"Automation Error (438). Object doesn't support this property or method"' when the code below runs. Can you help?

Code errors at

 .Open "http://collaborationcentre.sharepointname/Doc1.docx"

Private Sub Generate_Click()
    Worksheets("Message Templates").Activate
    Range("F10") = TitleTextBox.Value
    Range("G10") = SurnameTextBox.Value
    Range("H10") = ComboBox1.Value

Dim objWord As Object
Set objWord = CreateObject("Word.Application")
    With objWord
        .Visible = True
        .Open "http://collaborationcentre.sharepointname/Doc1.docx"
        .Selection.Goto What:=wdGoToBookmark, Name:="Title"
        .Selection.TypeText Text:=Range("F10").Value
        .Selection.Goto What:=wdGoToBookmark, Name:="Surname"
        .Selection.TypeText Text:=Range("G10").Value
    End With
End Sub