Hi everyone, I am using R.2.1.0 with limma 1.8.18 to read a "quantarray" .txt file. > RG <- read.maimages(file,source="quantarray") Error in "[.data.frame"(obj, , columns$Rf) : undefined columns selected The same data with the previous version of R (2.0.1) was working fine. Does anyone have a suggestion? Laurentiu