[BioC] compare function in CMA package

[Javier Pérez Florido]

Dear list,
According to the example given in "compare" help page for CMA package, 
I've executed the following code:

 ### compare the performance of several discriminant analysis methods
     ### for the Khan dataset:
     data(khan)
     khanX <- as.matrix(khan[,-1])
     khanY <- khan[,1]
     set.seed(27611)
     fiveCV10iter <- GenerateLearningsets(y=khanY, method = "CV", fold = 
5, niter = 2, strat = TRUE)
     ### candidate methods:  DLDA, LDA, QDA, pls_LDA, sclda
     class_dlda <- classification(X = khanX, y=khanY, learningsets = 
fiveCV10iter, classifier = dldaCMA)
     ### peform GeneSlection for LDA, FDA, QDA (using F-Tests):
     genesel_da <- GeneSelection(X=khanX, y=khanY, learningsets = 
fiveCV10iter, method = "f.test")
     ###
     class_lda <- classification(X = khanX, y=khanY, learningsets = 
fiveCV10iter, classifier = ldaCMA, genesel= genesel_da, nbgene = 10)
    
     class_qda <- classification(X = khanX, y=khanY, learningsets = 
fiveCV10iter, classifier = qdaCMA, genesel = genesel_da, nbgene = 2)
    
     ### We now make a comparison concerning the performance (sev. 
measures):
     ### first, collect in a list:
     dalike <- list(class_dlda, class_lda, class_qda)
     ### use pre-defined compare function:
     comparison <- compare(dalike, plot = TRUE, measure = 
c("misclassification", "brier score", "average probability"))
     print(comparison)
     ## End(Not run)

Everyhing is OK. However, if I add a new classification method using SVM 
like this:

class_svm<- classification(X = khanX, y=khanY, learningsets = 
fiveCV10iter, classifier = svmCMA, genesel = genesel_da, nbgene = 
2,kernel="radial")
classifierlist <- list(class_dlda, class_lda, class_qda, class_svm)
par(mfrow = c(4, 1))
comparison <- compare(classifierlist, plot = TRUE, measure = 
c("misclassification", "brier score", "average probability"))

I got the following error in compare function:
Error in `contrasts<-`(`*tmp*`, value = "contr.treatment") :
  contrasts can be applied only to factors with 2 or more levels

Any tips?
Thanks in advance,
Javier

 > sessionInfo()
R version 2.10.0 (2009-10-26)
i386-pc-mingw32

locale:
[1] LC_COLLATE=Spanish_Spain.1252  LC_CTYPE=Spanish_Spain.1252  
[3] LC_MONETARY=Spanish_Spain.1252 LC_NUMERIC=C                 
[5] LC_TIME=Spanish_Spain.1252   

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base    

other attached packages:
[1] MASS_7.3-3    class_7.3-1   CMA_1.4.1     Biobase_2.6.0 e1071_1.5-20

loaded via a namespace (and not attached):
[1] tools_2.10.0