Hi Jean-Yves, I have the same problem than you. > maqc <- read.xysfiles(xys.files) Loading required package: pd.hg18.60mer.expr Error in read.xysfiles(xys.files) : Must install the pd.hg18.60mer.expr package. In addition: Warning message: In library(package, lib.loc = lib.loc, character.only = TRUE, logical.return = TRUE, : there is no package called 'pd.hg18.60mer.expr' Have you got an answer to your question? Have you found a solution? Thanks a lot, Best regards, Alex ---------------------------------------------------------------- IRIC Montreal [[alternative HTML version deleted]]