I'm working on a paper with a logistic regression (logistics in Stata). One reviewer wants me to include an interaction term between two variables, which sounds reasonable. One of the variables is a categorical variable (1-4) with only very few values (2) in one of the categories the other is a binary variable. STATA runs into problems and omits it in the model and I can only show the margins when I use the following command, margins, dydx(VAR1) at(VAR2=(1(1)3)) thus practically only showing category 1-3 and not 4. Is there any convention how to report this in a journal or am I running into any fundamental problems I'm not thinking about at the moment?

I'd really appreciate your feedback! Thanks!