How come when I set my hair with ';swiss'; hair rollers, it didn't turn out tight and curly?

I sat under my big blow dryer for an hour and a half. I just bought them the other day. Their 25mm in size.They have a brush thing through the middle of them. How come when hairdressers can usually set my hair with those kind they can get it looking tight and curly and my mum couldn't?she set my hair. It should have turned out and had nice tight curls :-(. I have thick longish hair too and it has natural curls/waves hence why it always usually sets well and comes out tight and curly. Did my mum not wind the rollers right? Don't know what else it could be. She rolled the rollers length ways, isn't that how your suppose to roll them?How come when I set my hair with ';swiss'; hair rollers, it didn't turn out tight and curly?
You perhaps had too much hair in each roller or maybe did you not spray with hair spray before removing them.?