It looks like you need a bit study on what type of objects you are dealing with in AutoCAD. You can open AutoCAD, go into VBA Editor, open Object Browser window and see all the objects available in AutoCAD object model.
From the few lines of code, it is not clear what the "obj" is: a block reference (AcadBlockReference), or a circle (AcadCircle)?
If it is the former, then an AcadBlockReferece does nto have property like "CenterPoint..."; if it is an AcadCircle, it should have a property Center, but not CentrePointX/Y/Z and it does not have property "Name" or "EffectiveName"
So, you need to know WHAT AcadEntity or AcadEntities you are dealing with, and know what properties the target entity has.
Now, assume you are targeting a circle (AcadCircle), and needs to know its centre's coordinate, you do:
Range(...)=obj.Center[0]
Range(...)=obj.Center[1]
Range(...)=obj.Center[2]
Because Center propery is an 3-element array of Double values, representing X,Y and Z of coordinate
If you are targeting block, then there is no property Center, Instead, it has InsertionPoint property.
If you are targeting mixed entity types, you then need to treat them differently with the help of
If TypeOf obj is AcadCicle Then
''Do something
ElseIf TyoeOf obj Is AadBlockReference Then
....
Else
....
End If