Hi fiolks, any hint on why I get the error :

Error in log2(exprs(eSet)) : 
  non-numeric argument to mathematical function

>abatch<-ReadAffy()

>eSet<-mas5(abatch)

>eSet

ExpressionSet (storageMode: lockedEnvironment)
assayData: 22283 features, 8 samples 
  element names: exprs, se.exprs 
protocolData
  sampleNames: GSM31867_SKNMC.CEL GSM31867_SKNMC.CEL.gz ... GSM31870_SHSY5Y.CEL.gz (8 total)
  varLabels: ScanDate
  varMetadata: labelDescription
phenoData
  sampleNames: GSM31867_SKNMC.CEL GSM31867_SKNMC.CEL.gz ... GSM31870_SHSY5Y.CEL.gz (8 total)
  varLabels: sample
  varMetadata: labelDescription
featureData: none
experimentData: use 'experimentData(object)'
Annotation: hgu133a 

> SI<-log2(exprs(eSet))
Error in log2(exprs(eSet)) : 
  non-numeric argument to mathematical function

Is it exprs function - clash with dplyr problem (conflict with dplyr::exprs()) ?

Thank you very much Mr. Morgan. I have solved the problem by adding 

exprs=Biobase::exprs

to the top of the script.