Background coding

EXT. ABBEY GARDEN - DAY with OUTDOORLOOP
(Dara Amarie)
&overlay OUTDOORLOOP shifts to -640 0 in 5 THEN overlay OUTDOORLOOP shifts to -960 0 in 2.5 THEN overlay OUTDOORLOOP shifts to 0 0 in zone 2 in 0 THEN overlay OUTDOORLOOP shifts to 0 0 in zone 2 in 5 THEN overlay OUTDOORLOOP shifts to 0 0 in 2.5 THEN overlay OUTDOORLOOP shifts to 0 0 in 0 loop INFINITE times

My looping background appears and slides through the sequence then disappears at the end a second passes and then comes back. Why? My background is four zone, but it doesn’t seem to be the problem. It loops right, but there’s this big pause before it starts again. (reveals the nackground image) and then after three seconds or so loops back again.