I have been able to perfom gc-rma on the mu74av2 chips with v0.4 of gc-rma. When I tried using gc-rma on the m430a chip I got this error: >stu.gcrma<-gcrma(stu.ab) >Loading required package: moe430aprobe >Loading required package: matchprobes >background correction: gcrma >normalization: quantiles >PM/MM correction : pmonly >expression values: medianpolish >background correcting...done. >normalizing...Error in as.vector(data) : NA/NaN/Inf in foreign function call (arg 1) I was able to perform regular rma on the same affy batch object (stu.ab), so I don't think there is a problem with the ab object. Any suggestions? Akil