I am fitting a conditional risk model which is usually stratified by order of event and can't produce a predicted survival curve after my stcox model. Can someone help me out. I am getting an error that says "stcurve not allowed after stcox, strata()

See an example here demonstrated using Stata stan3 data. I did not stset as the data is stset already:

I want to predict survival at age=40 transplant=1 at two event levels that I have created:

Code:
clear
use http://www.stata-press.com/data/r15/stan3.dta

bysort id: gen event = _n

stcox age i.transplant, strata(event) cluster(id) nolog robust

stcurve, survival at1(age=40 transplant=1 event=1) at2(age=40 transplant=1 event=2)

stcurve not allowed after stcox, strata()
r(198);
Any advise will be appreciated