All my friends are bailing out on my plans!?

So this will sound nerdy but some friends and I were going to go rollerskating, it's really fun, at this rollerskating rink. And I didn't want to go alone with my little sister and her friend. So I invited two girls, one of which said she would come then said that she had made plans last week for tommorrow night. I said she should honor her committment and go ahead, then the second friend now says she can't go because of her dad coming in town and she wants to spend time with him so I said she should, all my other friends live to far away or wouldn't be into this kind of thing, but I have to go and don't want to go alone, what do I do?!?!