I am experimenting with the morphing feature. I know I am being very stupid but I cannot get the analysis to work. I am using a MAC OSX latest version. I have created my morph which is running nicely. What I would like to do is analyse the morph for VDW clashes. (That is in going from structure 1 to structure 2, what residues would have to move). First problem is when I run cluster (under analysis in MD movie) then generate residue interaction for cluster, up pop a new dialogue with warnings but seems to ask about calculations When I click OK or apply I get a new box residue interaction contact parameters This always generates an error “No atoms designated for clash detection’ I seem only to have four options themselves all others atoms (default) other atoms in same model second set of designated atoms Any help gratefully received (Ps I have installed the latest cytoscope but it does not have the structure.viz plugin; I keep getting errors trying to install older version) best Jim Jim Naismith The University of St Andrews is a charity registered in Scotland : No SC013532