svm error test data does not match model?

I'm trying to train an svm classifier to do prediction. When I try to use the trained model, I get this error: test data does not match model. I am not why this is happening. This is my code

# to prepare the training and testing data
dat = data.frame(x = rbind(tmp1, tmp2), y = as.factor(c(rep(1, 300), rep(-1, 300))))
set.seed(1)
train_ind = sample(seq_len(nrow(dat)), size = 500)
train = dat[train_ind, ]
test = dat[-train_ind, ]

# training and prediction
library('e1071')
svmfit = svm(y ~ ., data = train, kernel ='linear', cost = 10, scale = FALSE)
ypred = predict(svmfit, test)
table(predict=ypred, truth = test$y)