I would not worry about it, it took me about eight goes before I caught my first rabbits. If you know there are rabbits there and you did not catch, it could be down to a number of reasons, that are beyond your control. A fox could have walked the field just before you set the net, the rabbits are not out feeding at the time you set the net. The full moon would not have helped as the rabbits do not tend to wander far from home when the moon is full.
My advice would be go at a different time next time you do that drop give them and hour each side of the time you went. Say you went at 10 tr