Hey Rob,
How are you calling the sub? Like ChnageAllToLyer "0" ?

Oh well this will end the confusion Sorry

[VBA]
Sub ChnageAllToLyer()
Dim ssAll As AcadSelectionSet, mEntity As AcadEntity
Set ssAll = ThisDrawing.SelectionSets.Add("AllEntities")
ssAll.Select acSelectionSetAll
For Each mEntity In ssAll
mEntity.Layer = "0"
Next
ssAll.Clear
ssAll.Delete
Set ssAll = Nothing
ThisDrawing.Regen acActiveViewport
End Sub
[/VBA]