Strange. Daughters should know skype better than fathers. I bet she just don't want you to see her and her place. She could be undressed, have couple of boys with her, place could be in ruin after a rough night, etc.
Trust me, women these days knows skype and messaging better than anyone else, they use it the most. I highly doubt it's because her skype is messed up.
All you have to do is ask her to turn on her cam. If she says no or gives any excuse, tell her you'll give her a call back in an hour.