[PyMOL] Transparency of VASCo surfaces

Hi all,

I often use  VASCo surfaces and I am experiencing a strange behaviour on transparency settings as VASCo surfaces do not "respond" to:
set transparency, value, object 
Not from the command line, not from the plugin itself. Pymol's surfaces get transparent but not the object corresponding to VASCo surface.
I am not sure but I would say it worked to me before. 
I am on pymol 1.5.0.3 on a Macbook pro 2011 (Pymol Hybrid).


Am I missing something? 

thanks and regards

Gianluigi