Error: Recommender method UCBF not implemented for data type realRatingMatrix.

Code -
train = sample(x = c(TRUE, FALSE), size = nrow(Jester5k),replace = TRUE, prob = c(0.8, 0.2))
dataset_train = Jester5k[train,]
dataset_test = Jester5k[!train,]
rec_model = Recommender(data=dataset_train,method="UCBF")
Can someone help me with this error.