[PyMOL] electron density map manipulation

[Dieter Blaas]

Hi, I have been trying to visualize a DN6 electron density 
map. Although it is read in apparently correctly nothing 
shows on the screen. Are there any particular 
parameters to be set? I can visualize it in 
SwisspdbViewer but I was unable to produce surface 
rendering. Can Pymol produce a surface at a particular 
cut-off value as can Amira?
Thanx for hints, Dieter