You can't set size to 9. You have to use one of the available constants:
Sub ScratchMacro()
'A basic Word macro coded by Greg Maxey
'Select your line and name it with this code:
Selection.ShapeRange(1).Name = "Line"
'Then stet out that line and process with:
With ActiveDocument.Shapes("Line").Line
If "heads" = "heads" Then
.BeginArrowheadStyle = msoArrowheadNone
.EndArrowheadStyle = 2
.EndArrowheadLength = msoArrowheadLong
Else
.EndArrowheadStyle = msoArrowheadNone
.BeginArrowheadStyle = 2
.BeginArrowheadLength = msoArrowheadLong
End If
End With
lbl_Exit:
Exit Sub
End Sub