[BioC] ComBat error message

[Ingrid Dahlman [guest]]

Why do I get an error message when running ComBat?

Target file:
SAMPLE DAYPREP HOMA
x5794       1   IS
x5803       1   IS
x5810       1   IR
x5811       1   IR
x5828       1   IS
x5829       1   IS
x5834       2   IR
x5849       2   IR
x5857       2   IS
x5859       2   IS
x5861       2   IS

library (limma)
library(Biobase)
library(statmod)
library(sva)
eset.txt<-read.delim("eset.txt",header=TRUE)
target<-read.delim("target.txt",header=TRUE)
eset<-readExpressionSet("eset.txt","target.txt",header=TRUE)
HOMA <- factor(target$HOMA, levels=c("IS","IR"))
batch <- target$DAYPREP
design <- model.matrix(~as.factor(HOMA), data=target)
combateset <- ComBat(dat=eset, batch=batch, mod=design)

 -- output of sessionInfo(): 

Found 2 batches
Found 1  categorical covariate(s)
Standardizing Data across genes
Error in dat - t(design %*% B.hat) : 
  non-numeric argument to binary operator
In addition: Warning message:
In is.na(dat) : is.na() applied to non-(list or vector) of type 'S4'

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