Thank you for your assistance.
I have fitted the following model using the "multinomial" distribution:
> fit.step<- gbm.step(
+ data=data.gbm,
+ gbm.x = 2:num.col.data.gbm,
+ gbm.y = 1,
+ family = "multinomial",
+ tree.complexity = 5,
+ #n.tree = 100,
+ #max.trees = 1000,
+ learning.rate = 0.005,
+ bag.fraction = 0.5
+ )
But I keep on getting this error message: "Error in total.deviance/n.cases: non-numeric argument to binary operator"
What could be the problem?