[Koha] Advanced Pattern for Serials Help

I have this serial that comes every other month and is number like this Vol 1 Num 1/2, Vol 1 Num 3/4. I have this pattern in place, but it's not quite working. See the screenshots here: http://screencast.com/t/exxF7ekCw And the pattern I used is here: Values for X Add : 1 once every: 6 other values should be ok Values for Y Add : 2 oncer every : 1 When more than 12 Set back to 1 Values for Z Add : 2 oncer every : 1 When more than 12 Set back to: 2 Any ideas on this? I've been working on it for ages now and have had no luck - I don't know why it's not working. Thanks in advance! Nicole