Hello everyone,
I hope you're all doing fine.
Firstly, I wanted to express how grateful am I for your kind help, it really helped me very much as a beginner. Thanks a lot, I really appreciate it.

Secondly,

I've used the following command
Code:
stptime, by(rs2228001) per(100)
stmh rs11615, compare (0,2 )
I keep getting this error:
variable RR already defined
variable Lower not found


when I'm trying to get Mantel–Haenszel estimate of the rate ratio between 0 and 2 values of rs11615 using the command

where rs11615 is a categorical variable with three values 0,1,2

Before that, I've done many survival time analyses as Kaplan Meier, and they all went pretty fine, but this one keeps getting this error.

How can I avoid that error ?