Dear Professor, Sorry for my ignorance and poor English. In order to extract my data of interest later, I should load annotation using : phenoData(raw)<-read.AnnotatedDataFrame(pd) eset<-rma(raw) After these, the error occurs as bellow: > traceback() 5: stop(paste(msg, paste(paste(seq_along(errors), errors, sep = ": ")), collapse = "\n"), domain = NA) 4: validObject(out) 3: .local(object, ...) 2: rma(raw) 1: rma(raw) > sessionInfo() R version 2.13.0 (2011-04-13) Platform: i386-pc-mingw32/i386 (32-bit) locale: [1] LC_COLLATE=Chinese (Simplified)_People's Republic of China.936 [2] LC_CTYPE=Chinese (Simplified)_People's Republic of China.936 [3] LC_MONETARY=Chinese (Simplified)_People's Republic of China.936 [4] LC_NUMERIC=C [5] LC_TIME=Chinese (Simplified)_People's Republic of China.936 attached base packages: [1] stats graphics grDevices utils datasets methods base other attached packages: [1] pd.090319.zea.kr.exptil_0.0.1 RSQLite_0.9-4 [3] DBI_0.2-5 oligo_1.16.0 [5] preprocessCore_1.14.0 oligoClasses_1.14.0 [7] Biobase_2.12.1 loaded via a namespace (and not attached): [1] affxparser_1.24.0 affyio_1.20.0 Biostrings_2.20.0 bit_1.1-7 [5] ff_2.2-2 IRanges_1.10.0 splines_2.13.0 Thank you! Warm Regards Maggie [[alternative HTML version deleted]]