Hi,
I have created an affybatch object from 3 cel files. The files have data
from Affymetrix's Mouse Expression (Oligonucleotide) array.
Affybatch object was created by command:
testAffy <- ReadAffy()

In the next step I tried to use expresso to adjust background using RMA and
normalize using loess, using the command:
testAffy.loess = expresso(testAffy, bgcorrect.method= "rma",
normalize.method= "loess")
Here is the output:
background correction: rma
normalization: loess
PM/MM correction :
expression values:
background correcting...done.
normalizing...Done with 1 vs 2 in iteration 1
Done with 1 vs 3 in iteration 1
Done with 2 vs 3 in iteration 1
1 0.0176947
done.
Error in function (classes, fdef, mtable)  :
  unable to find an inherited method for function "computeExprSet", for
signature "AffyBatch", "NULL", "NULL"

The testAffy.loess object was not created.  Any idea why I am getting an
error on running the expresso command?
Thanks in advance.
Anjan

-- 
===================================
anjan purkayastha, phd.
research associate
fas center for systems biology,
harvard university
52 oxford street
cambridge ma 02138
phone-703.740.6939
===================================

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