Thanks for the reply Michael.
I tried to activate V21 with my V20 License key and it didn't work. Gave an 'unknown error 1030'
I thought that would work as I am still in year 1 maintenance.
Any other ideas would be helpful.
Further to my original post I have had a go at some coding.....see below
Dim unit As Acad3DSolid
Dim bpoint As Variant
Dim ucgp As Variant
Dim uvolm As Variant
Dim cgx As Variant
Dim cgy As Variant
Dim cgz As Variant