Your code with Graham's revisions inserts a table "AT" a bookmark. If you want to "WRAP" the table "IN" the bookmark use:
Code:
Sub ScratchMacro()
'A basic Word macro coded by Greg Maxey
Dim oRng As Word.Range, oTbl As Word.Table
Set oRng = ActiveDocument.Range.Bookmarks("InsertDuty").Range
Set oTbl = ActiveDocument.Tables.Add(Range:=oRng, NumRows:=3, NumColumns:=4)
ActiveDocument.Bookmarks.Add "InsertDuty", oTbl.Range
lbl_Exit:
Exit Sub
End Sub