I got the following error when using RMA command: > data<-ReadAffy() > data AffyBatch object size of arrays=712x712 features (23767 kb) cdf=HG-U133B (22645 affyids) number of samples=6 number of genes=22645 annotation=hgu133b Warning message: package hgu133bcdf was built under R version 2.0.0 > set<-rma(data) Background correcting Normalizing Calculating Expression Error in rma(data) : dimnames applied to non-array Please tell me what the problem is? (My guess is that the hgu133bcdf was built under R 2.0 but mine is 1.91.) When I retry the same command again, and it worked the 2nd time. I don't know if I can ignore the error message and trust the normalized data. Thanks. L