预测时使用R在h2o.randomforest中显示警告消息

Question

In my following R code , i am getting an warning message in predicting values in the test data

train <-h2o.assign（training，“ train.hex”）
  测试<-h2o.assign（testing，“ test.hex”）

#####
rf<-h2o.randomForest(
  training_frame = train,
  x = 1:32,
  y = 33,
  ntrees = 50,
  score_each_iteration = T,
  stopping_rounds = 2,
  seed=999999)

    summary(rf)
    predictions<-as.data.frame(h2o.predict(rf,newdata=test))

    submission<-data.frame(unique_id=test$unique_id,target=predictions$predict)

    #Warning message : test/validation dataset column '' has levels not trained on