"...going elsewhere, like to school" - you would use the noun "work" (el trabajo) to say that.
Ellos no van al trabajo. No van a la escuela. No van a la playa. Etc.
In this example, they are using the "ir + a + infinitive verb" construction, which is like a simple future tense.
No van a trabajar - not going to work, as in not going to perform the actions of work.
Another example: No van a comer - they are not going to eat
Maybe you put "van ir" instead of "van a ir" which would be the correct way of saying it. It sounds redundant in a direct translation, "going to to go", but it is proper that way. Also Duolingo may have just been picky about your addition of an extra ir? If that is the case, then your answer would be correct and understood by speakers, but not to duolingo.
To me, in English. "The persons are not going to work" is correct in English. So I find it okay to translate literally to understand this phrase better. Each individual person of a group is not going to work. Its almost like "People under 21 are not allowed to enter" vs "Persons under 21 are not allowed to enter".