Hey there, Kaienkus. Getting down a solid system for workzones throughout your zoo can take a while to learn, as I'm assuming you're a new player. Your problem could be that you have no staff rooms in the workzone, or no shops in the workzone. Also, just make sure you have vendors assigned to a workzone.
Since I'm an extremely organized person, my workzones are very organized. Each workzone is titled "Keepers-Koalas" or something along those lines. Basically "the name of the type of staff-what you're using them for". So for vendors, I would set it up as "Vendors-Food Court (for example)". Then, take the amount of shops you have, let's say 4 for example, then half that number and add it onto 4. So that would be 6, and that's the number of staff members you need for the workzone. This ensures that a shop won't be unattended for a long period of time.
If you have any other questions, ask me!