Ok, I have tried sending this to the cns board and it has been reject with my old email and new email addresses so I will try here and sorry for the non ccp4 question. While compiling CNS 1.21 on an older systems running Redhat Enterp. 4 the following error comes up. machine_f.o(.text+0x11ca): In function `vopen_': : undefined reference to `rename_' collect2: ld returned 1 exit status problems with new executable - old version retained This is a fresh install on this machine. Any ideas would be appreciated. Thanks, Leonard Thomas Ph. D. Macromolecular Crystallography Laboratory Manager University of Oklahoma Department of Chemistry and Biochemistry 620 Parrington Oval Norman, OK 73019 [log in to unmask] http://barlywine.chem.ou.edu Office: 405-325-1126 Lab: 405-325-7571