Floorspacebuffer

Hello. I´m trying to use a FloorSpaceBuffer. It is linear and the BufferMode is FIFO, with 7 slots.
i dont want the feeder to repeat the slots that have already been emptied untill the hole set is taken out. The problem is that the AGV transports out the container from the first slot before the feeder puts the container in the second slot, so it fills the first one instead of the second one because its empty.