Playback of repeats

Ive got a phrase which I want to repeat four times and all is fine (been to the last measure and clicked properties and repeat x 4). On the last repeat I want to have a slightly different measure. Just trying to get the playback to work with Volta lines (at present the issue is that the Volta lines dont play x 3 and then go to the 4th version). How do I get playback to recognize do this 3 times but on teh 4th play the alternative measure? thanks in advance!