[gmx-users] WARNING: could not find a Van der Waals radius for 260 atoms

[Yuhua Song]

Dear Gromacs mailing list:

When I try to use Gromacs 3.2.1 version to use: g_sas to calcualte the area per headgroup of lipid, during using "g_sas", it shows the warning information:
"WARNING: could not find a Van der Waals radius for 260 atoms", when I open the atomarea.xvg (generated file), it shows that the area for some atom is zero, 
when I track these atoms, they are not special atoms, just N, O atoms. 

So, could you please give me some hints about what causes the warning information? or have you met such warning inforation before?

Thanks,

Yuhua