conditional rules do not work on "next" click

As far as I understood conditional rules, they only work, if one clicks next AND the rule has a match, correct?

My problem is, that this doesn't seem to work properly. E.g.:

I have a radio button question whether the expectations on a booked training have met or not, the user has three options:

not_met|Not met
partially_met|Partially met
met|met
exceeded|exceeded

after that (in the same area, i.e. before a page break), I add a text field to ask what the problem was if the user chooses net_met or partially_met.

When I now go into the form, fill it and choose "not_met" and click next, I don't get the textfield, it just jumps to the next page. When I the click "back" (in the form, not the browser), the textfield appears, but it always appears when clicking back no matter what one has chosen.

I'm I missing something?

thanks

Andre