Dear all,

I am trying to perform a multinomial logistic regression with fixed effects (I am working on panel data), running the femlogit command, but I got the following error message: "factor-variable and time-series operators not allowed". I don't see what part of my code or data I should change/modify to make this model work.
This is my regression:
femlogit BROWNISH_MULTI l(1).(BERD_AUTO CAR_SALES Log_PATENT_STOCK GREEN_GOV_RD REN_EN_PUB_RD FOSS_FUEL_PUB_RD BEV_SALES EPS GDP_PC), group(ID_COUNTRY) base(0)

Thanks in advance for any help/advice!
AN

PS I am using STATA 15.1