getting this error in Caret

Question

I\'m getting the following error and I don\'t know what may have gone wrong. I\'m using R Studio with the 3.1.3 version of R for Windows 8.1 and using the Caret package for

Answer 1

It is probably due to having about outcome factor with levels "0" and "1".

There is a specific warning issued when this happens: At least one of the class levels are not valid R variables names; This may cause errors if class probabilities are generated because the variables names will be converted to: X0, X1"

It seems that people uniformly ignore warnings so I'm going to make this throw an error in the next version.