ODK error message

[mathieubossaert]

I understand.
You have another option to loop inside the crop repeat until the user select "no more crop" :

XLS form- Repeat select_one question until "A" is selected

It should be something like if (${count} = 0 or (/indefinite-repeat/person[position()=${count}]/choice != 'a' and /indefinite-repeat/person[position()=${count}]/age >= 50), ${count} + 1, ${count}) We're defining a continuing condition so we need to reverse your ending condition. You want to end when "a" is selected or age < 50 so the negation is to continue as long as "a" is not selected AND age is greater than or equal to 50. If you want to know more about why the or becomes an and, …

Maybe first start with your version and upgrade the form if needed later.
Start with your version, You will be able o upgrade it.