Well, she's 4. Four year olds are, you know, 4 year olds. So what kind of behavioral problems are you talking about? What "bad" things is she doing? Trying to see the severity here.
Encourage her to be "Self aware". She may not be able to stop her behavior, but if train her to become aware of herself, her inner emotions, that self awareness will come in handy later on in life.
Not necessarily trying to 'change' her behavior or figure out 'why', instead trying to get her to 'notice' her own behavior.
(Change may come naturally after noticing, though may take 2 weeks, I don't know why, but I've read it takes 2 weeks for the brain to rewire itself.)
"I ask her why is being bad"
I don't think you should tell her that she is bad. It is ok to say you are doing something wrong or bad, but it is best to avoid labeling her since she may start thinking she is a bad person when in fact she is likely a nice person who is making a mistake.
You know, I had a really tricky toddler. What a wonderful, beautiful boy he was but he was a handful. He's 16 now, they do eventually grow up. :>) What is your child doing and we can try to help! I do agree that I try to stay away from calling a child bad. You say the behavior or what they are doing is wrong or bad but not them. I found in parenting my two boys that praise is very powerful in directing a child to appropriate behavior and the power of giving them choice works great. You give them three options, all that you are okay with, they pick one of the three options and they feel like they have some control. win win. But tell us more, and we'll help!