Having trouble getting my girls to go to clubs

[ILoveVacation!]

I dont know what the problem is, but after 2 cruises, my 12 yr old girls will not go to the clubs. I am looking for cruise buddies for the Feb 20 2011 mexican riviera cruise. They are normally outgoing, athletic, and a lot of fun, but because they are twins, they dont feel like they have to get away and make some friends. HELP.