setwd("d:/Program Files/RStudio")
library("glmnet")
library("survival")
data<- read.table("aaa.txt",head=T,sep="\t")
options(stringAsFactors=F)
surv<-Surv(data$time,data$death)
some_matrix<-data.matrix(data[,3:58])
fit <- glmnet(some_matrix, surv, family="cox", alpha=1)
运行时出现错误，求大神们帮忙看看，谢谢
Error in coxnet(x, is.sparse, ix, jx, y, weights, offset, alpha, nobs,  :
  negative event times encountered;  not permitted for Cox family