clogit and odds ratio curve using R

I am trying to plot a continuous variable effect as an odds ratio (OR curve over a continuous variable with restricted cubic spline) using clogit(conditional logistic regression) in R.

ddist\$limits["Adjust to","var1"] <- 30
model <- clogit(case ~ rcs(var1, 4) + strata(statu), data = data1)

predicted <- Predict(model, var1, ref.zero=TRUE, fun=exp)


But I keep getting an error message:

Error in Predict(model, var1, ref.zero=TRUE, fun=exp): predictor(s) not in model: var1


When I am running this using LRM, I don't see this error message though. Am I supposed to use different codes when using clogit?

Thank you