# probsoln package FAQ

Label ... undefined 🔗

You need to define a problem before you can use it. Check to make sure you haven’t mis-spelt it, and check to make sure you have used the file in which it is defined either via `\input`, `\loadallproblems` or `\loadselectedproblems`. If you have used `\loadrandomproblems`, you shouldn’t try referencing a problem since there’s a chance it may not have been selected.

2020-07-03 11:12:04