R错误 predictor not in model

setwd('c:/myr')

getwd()

data = read.csv(file='c:/myr/Wage.csv')

age.logit = data$age

wage.logit = vector(length = length(age.logit))

for (i in 1:length(age.logit))

{

  if(data$wage[i] > 200)

    wage.logit[i] = 1

  else

    wage.logit[i] = 0

}

#data for logistic model

data.logit = data.frame(age.logit, wage.logit)

###################################################

library(splines)

###################################################

#generate 3 pieces of spline basis , plot

###################################################

bspline = bs(age.logit, df = 3)

data.plot = cbind(age.logit, bspline)

data.plot.sort = data.plot[order(data.plot[, 1]), ]

matplot(age.logit, bspline)

matplot(data.plot.sort[,1], data.plot.sort[, 2:4], type = "l")

###################################################

#logistic cubic spline regression

###################################################

fit = glm(wage.logit ~ bs(age.logit, df = 3), family = binomial(link = "logit"))

summary(fit)

fit=update(fit)

#logit prediction

newdata = seq(20,60)

newdata1 = list(age.logit = newdata)

n<-1000

age<-50+12*rnorm(n)

pred = predict.glm(fit, newdata = list(age.logit = newdata),se.fit = TRUE)

HRpred = Predict(fit,newdata,fun=exp, ref.zero = TRUE)   #报错

Error in Predict(fit, newdata, fun = exp, ref.zero = TRUE) :

  predictors(s) not in model: newdata

为什么使用Predict就不行呢