R help - Dec 2012 - Package party Error in model.matrix.default(as.formula(f), data = blocks) :allocMatrix: too many elements specified

Dear all:
         I¡¯m trying to get unbiased feature importance of my data via package
¡°party¡±, which contains 1-5 integer value, and a few numeric values
attributes. The class label is 1-5 integer value as well. In total I have 20
features with 1100 observations. I checked the type my data in R using
class(my_data_cell), no factor has been observed. I received a commond error
like others did from the past.
> lu = read.csv(file=file.choose())
> lu.cf <- cforest(Target ~ ., data = lu, control =  cforest_unbiased(mtry
= 2, ntree = 50))
> lu.cf <- cforest(Target ~ ., data = lu, control =  cforest_unbiased(mtry
= 2, ntree = 100))
> cvi_lu = varimp(lu.cf,threshold = 0.2,conditional= TRUE,OOB=TRUE)
Error in model.matrix.default(as.formula(f), data = blocks) :
  allocMatrix: too many elements specified

Anybody please given suggestion? Thanks a lot!

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