As your children get older, you start to realize disciplining is an art form. Your children change and their punishments and rewards have to be altered with them or there will be chaos. What use to work, may no longer work to get their attention. Disciplining is all about trial and error along with persistency.
One of the biggest fights as my daughter gets older is bedtime. She thinks when school is out she should be able to stay up until she is tired. With that philosophy, she would go to bed close to never. So other than a 101 arguments, from both of us, I had to resort to taking things away from her.
My daughter is at an age where electronics and playing with friends or me are extremely important to her. If she stays up late to play on the computer or her DS, they will be the first thing I take away from her. If she stays up past when I want, the next day I do not play with her with the explanation that without sleep people cannot function to the best of their ability and I am too tired to play. Although this might make her upset, she gets the point that her actions have consequences.
Discipline is the hardest part of parenting. No parent wants to be the bad guy, yet in order to mold our children into the best people they can be we have to teach them right and wrong. There is no right way to discipline. Trial and error are a part of parenting. So if your discipline technique is not working try, try again.