我正在使用机器学习的SVM方法。当我使用模型对测试数据集进行预测时，我得到了所有NA。我认为问题出在kernlab。我该如何处理？任何建议将不胜感激。谢谢

library(e1071)

library(kernlab)

model_svm<-train(nzv[index,],trainSet.y,method='svmRadial',trControl=fitControl,tuneLength=6)

testSet$model_svm <- predict(model_svm,testSet)

testSet$model_svm <- predict(model_svm,testSet) Warning message: In method$predict(modelFit = modelFit,newdata = newdata,submodels = param) : kernlab class prediction calculations failed; returning NAs

  

testSet $ model_svm    [1]   [25]   级别：N Y