Thanks to the user karan chanana, his solution is: I found the solution for this problem. of facebook app

1. Thanks to the user karan chanana, his solution is:
I found the solution for this problem.
The application platform should be enabled in the facebook account as Ovi by Nokia is one of them.
I had it disabled for reducing spams.
In your Facebook account, Go to
Account
Privacy Settings
Edit your Settings under "Apps and Websites" at lower left corner
Click Turn on all platform apps.
Then your facebook will login under Social Networking Client provided by Nokia without "Invalid
username or password. Tip. Password is case sensitive."
I created a new facebook account and it logged in the very first time and i knew it must have been the
account security or application platform. The latter was the one. <