I want to load two files, one for the protein and the other for the ligand. This is, of course, not a problem. The question is how do I get both files to be present as choices in Select/Chain? Some times both of them are there, but at other times only the first one that I loade. -- Stephen P. Molnar, Ph.D. Life is a fuzzy set Foundation for Chemistry Stochastic and multivariant http://www.geocities.com/FoundationForChemistry