Why can't I find my sim's ID?

I have tried finding my sim's ID (with the sims.get_sim_id_by_name command) but nothing shows up. It works for other sims, like her husband, whose ID shows up immediatly. It's not like I'm spelling her name wrong, either, cause it tells me when I do.

I'm wondering if it has something to do with me changing her name. I have tried with her original name, but it tells me it can't find the sim, like it always does when I spell something wrong. When I use her current name, nothing at all happens. The fact that there is no error message, makes me think that is the name I should use, but I don't get her ID?

Do you know why that keeps happening?