Can't make in-app purchases! Driving me crazy?

I can download songs and apps fine, but when it comes to in-app purchases, when I put my password in, it tells me something along the lines of, "The Apple ID you've entered couldn't be found or the password is incorrect."

It's infuriating because I know I'm putting my password in correctly.

I have the iPhone 4.

Check with your phone provider. Why purchase Apps, most of them are free. But check anyways.

Make sure in settings it's not turned off…
Settings -> General -> Restrictions and make sure that the ability to make In-App Purchases wasn't turned off in that section or that you are authorized to get a purchase based on content rating. Might surprise you.

If still no good… A hard reset and backup of iTunes and/or call them.
http://www.apple.com/...s/contact/

Best luck.

Try resetting your password if none of the above work. If you don't want to, close down iTunes, give it a day, and check again. It's the most basic thing you could do.

Hi
Sometimes it gives the system error. Kindly contact for Apple help only an agent can guide you well you can either visit Apple store and ask for help or call them. I'm sure this will solve your problem.