'mixlogit' and 'gmnl' commands not working with binary dataset


My thesis is about Hybrid choice and multinomial logit. I´m using both commands 'mixlogit' and 'gmnl' in Stata for a dataset that:

- Includes 12 choice tasks per person (a total of 81 respondents).
- 3 different choices for each choice task
- Just one answer must be selected (each respondent will get 12 answers)
- Answers no selected are equal to 0 and the selected answer is equal to 1 (In each choice task there will be two 0 and one 1)

In the image, the commands include one dependent variable "choice" and

Both commands should accept that the same respondent chose 12 times an option (among the three available) but it appears "At least one group has more than one chosen alternative".

I don´t know if the dataset don´t recognise that each person replies 12 times... Any suggestion? Thanks!