I have a challenge lately with constraints. I will try to be practical as possible.
I have the first two variables noofMales and noofFemales which should not be both zero ie noofMales+noofFemales <> 0. Then after that I have MalesinHHAV and FemalesinHHAV which should be a total of at least 1 depending on the population captured in the first 2. On testing on the Enketo, using the constraint noofMales + noofFemales = 0 on the noofFemales it works but on the tablet, it gives an error.

Secondly, how can I prevent the user from inputting 0 on all four?

Hi, kindly upload a snapshot of your xlsform with constraints as you have written them. I will be ready to help you on this.