Opening an ACAD drawing Error: MDI mode!

I can't seem to open an Autocad drawing in VBA. i keep getting a Collection not available in MDI mode error. Use documents. Here's the code I'm trying to run.

VB Code:

Set acad = CreateObject("Autocad.Application")
    Set acad = GetObject(, "AutoCAD.Application")
    acad.Visible = False
    
'Hide the dialogue box
    Set acaDoc = acad.ActiveDocument
    acaDoc.Open "C:\Projects\W7ls0116.dwg"
    Set pViewport = acaDoc.ActiveViewport
    pViewport.ZoomExtents
    Set sset = acaDoc.SelectionSets.Add("NEWSS")
    sset.Select acSelectionSetAll Set acad = CreateObject

You should only need the 1st line rather than the top 2 - try commenting out the 2nd line to start with.

What line does this fall over on? & what is the bottom line there meant to do please?

Hope this will work...

Code:
--------------------------------------------------------------------
Dim acadApp As AcadApplication

Set acadApp = GetObject(, "AutoCAD.Application")
If Err Then
Err.Clear
'Open AutoCAD app if not already open
Set acadApp = CreateObject("AutoCAD.Application")
acadApp.Visible = True
If Err Then
MsgBox Err.Description
Exit Sub
End If
End If