Hi, As Benilton pointed out, you have a stale version of affyio. This suggests that you reused your package library while upgrading R and BioC. I thought I would take the opportunity to make a recommendation for upgrading R and BioC... I would strongly recommend maintaining separate package libraries for each version of R and Bioconductor. This will help one avoid subtle (and not so subtle) version mismatch issues. After an initial install into a _new_ pacakge library, you can update the set of installed packages like this: library("Biobase") update.packages(repos=biocReposList()) + seth -- Seth Falcon | Computational Biology | Fred Hutchinson Cancer Research Center http://bioconductor.org