[BioC] subtractmm problem in "affy"

[PARK,CHRISTOPHER CHANGSUN]

Hi all,

I am trying to normalize microarray data using the subtractmm method using
the "affy" library.

The following is my R script:

set.seed(123)
library(affy)
Data <- ReadAffy()
eset<-expresso(Data,bgcorrect.method="rma",
normalize.method="quantiles",
pmcorrect.method="subtractmm",
summary.method="medianpolish")
write.exprs(eset,file="subtractmm_data.txt")

During the normalization, I encounter the following error message:

Error in if (converged) break : missing value where TRUE/FALSE needed
In addition: Warning message: 
NaNs produced in: log(x, base) 
...

The processed data is a grid of NA's.

Does anyone know what might be wrong here and what I could do to fix it?

Thanks again for your help,
Chris