Hi,

Any advice for this problem please ?

> dat<-ReadAffy()
> dat

AffyBatch object
size of arrays=1164x1164 features (20 kb)
cdf=HG-U133_Plus_2 (54675 affyids)
number of samples=9
number of genes=54675
annotation=hgu133plus2
notes=
> dat2<-rma(dat)
Error in (function (classes, fdef, mtable)  : 
  unable to find an inherited method for function ‘rma’ for signature ‘"AffyBatch"’

why that Error with (rma) function ??

#Tahani

Most likely because you loaded the oligo package after you loaded the affy package, and now you are masking affy::rma() with oligo::rma(). In that situation you can just do

dat2 <- affy::rma(dat)