Problem with xtpdyn

[Antonio Stanco]

I am trying to estimate a probit model with xtpdyn.
However, when I run

xtpdyn hnpl gdp lir capad roa, uh(gdp)
xtpdyn, keep
 margins, dydx(capad gdp) expression(normal(predict(xb))) force

I get an error

. xtpdyn, keep
one or more variables already defined

I uave written that this may be caused by the presence of "_" in the name of the variable but this is not my case. If I replicate the command on dataset implemented in Stata by webuse, I don't get any error.

[Antonio Stanco]

Solved, the problem was that I have my panel identifier with an underscore.

Sorry for bothering you.