error in cv.glmnet()

[lovelymaoqin]

Hi,

I got a error when I ran
cv_output <- cv.glmnet(x_vars[train,], y_var[train],
alpha = 1, lambda = lambda_seq,nfolds = 5)

Error in elnet(xd, is.sparse, ix, jx, y, weights, offset, type.gaussian, :
y is constant; gaussian glmnet fails at standardization step.

Can someone help me out?

Thanks,

maomao