Most likely by your actions you've taught the child that they don't have to listen to you.

I've been a parent. There were immediate consequences for slow obedience or outright defiance. I believe in spanking. It's a disciplinary tool but not the only one. You have to know your child and use what's best. Some children are so sensitive that making them stand in the corner for 30 seconds is enough to correct their behavior. You need to teach your child to fear the consequences of disobedience.