The dataset used here has also been used in another model and it worked. Also, the C5.0 method has been used with another dataset and worked as well:
> fitControl<-trainControl(
+ method=cv",
+ number=10)
+ set.seed(100)
+ c50Fit<-train(class~.,data=Train,
+ method="C5.0",
Error: unexpected string constant in:
"c50Fit<-train(class~.,data=Train,
method=""
>