Try to schedule a double lesson.......

[Traceyb]

Im trying to schedule a double lesson on Nova T6 but when I go to the 'block' screen and try and move the lesson into place it comes up with 'period overflow in group..... in sessions of length 2 or greater'. If I try and manually drag it over I get the following: in period 'break' in details 'overrun'. Ive had a look at my cycle and I cannot see how it over runs with the break?

Any help would be great, this is the first time im building the timetable and I cannot find any help in the manuals?!