Lock Document

I am using AutoCAD 2014 and vb.net 2010 and coverting code from 2010 to 2014.

This like does not work anymore.

Using locked As Autodesk.AutoCAD.ApplicationServices.DocumentLock = ThisDrawing.LockDocument()

Any clue as to why?

These are the lines for ThisDrawing

Public ReadOnlyProperty ThisDrawing() AsDocument

Get

ReturnApplication.DocumentManager.MdiActiveDocument.GetAcadDocument()

EndGet

EndProperty

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