Dear Uwe, I appreciate that if you let me know why, when using the attached file, the following script (two lines) doesn't work once in 10s of times. Best, Reza svm.pol4 <- ksvm(class.labs ~ ., data = train.data, prob.model = T, scale = T, kernel = "polydot") svm.pol.prd4 <- predict(svm.pol4, train.data, type = "probabilities")[,2]