You may get this error message even though Class Search shows there is a seat available because the system is giving priority to student(s) who have placed themselves on this course's Waitlist.
For example, when a seat becomes available to Student1 on a Waitlist, an email notification is sent to that student letting them know a spot has become available, and a deadline to register for this 1 spot. The system is giving priority to student1, and allowing him/her time to register for the open seat. If Student1 does not register for the course within the allotted time, the system moves on to Student2 and the process repeats.
In the example above, the one (1) seat remaining (circled in red) is open only to the students who have been on its waitlist. Class Search shows there is a waitlist for this course under the Waitlist Capacity, Waitlist Actual and Waitlist Remaining columns.
Do not attempt to register for a class that has a Waitlist count unless you have personally received the email to your FIT account, informing you that there is a spot available.