Changing the layer of drawing centre marks and dimensions

Hello, I'm trying to automate the drawing of some parts. As part of this I am trying to change the layer of both the dimensions and the centre marks to match my company's standard template. The drawing templates are pre-imported into the drawing, so I would want to change say the centre marks layer from its default to the layer called "CENTRE". So far I have been having no luck. What I think should work is shown below, but it keeps on getting stuck at the GetSelectedObject6 stage. Does anyone have any ideas of what is going on? Am I barking up completely the wrong tree? Will it work if I sort out the GetSelectedObject6 problem or does it need something else.

Dim Draw As SldWorks.DrawingDoc

Dim swSelMgr As SldWorks.SelectionMgr

Dim swDrawComp As IDrawingComponent

boolstatus = Draw.ActivateView("Drawing View2")

boolstatus = Draw.Extension.SelectByID2("DetailItem129@Drawing View2", "CENTERMARKSYM", 0.0664070846066, 0.1201125333933, 0, True, 0, Nothing, 0)

Set swSelMgr = Draw.SelectionManager()

Set swDrawComp = swSelMgr.GetSelectedObject6(1, -1)

swDrawComp.Layer = "CENTER"

Thank you

SolidworksApi macros