This is a common question from new TimeForge users, and there are two easy answers:
Either you do not have breaks turned on in TimeForge, or the employees are not meeting the criteria specified in your break rules.
For instance, if your break rules state that employees aren't allowed to take a break unless they've been at work for two hours, they won't be given the option to take a break in TimeForge until they've been clocked in for two hours.
Make sure your employees know what your break rules are!
This goes for your management team, too. Make sure everyone's aware of what your company's break rules are, so that they aren't confused when they discover they can't take a break.