Cant log in to Twitter via the settings on my iPhone 4S

I have within the last few days, changed my password on my Twitter account. I went to the settings app on my 4S and went to the Twitter section and went to log in with my new details for my account, but it wont let me log in. I can enter my Twitter usernam and password and I get the 4 ticks appare on the screen and then when I go to my Twitter app I get a message to go back to the settings app and re-enter my Twitter password. This I have done now several times and still nothing. I have all so tried to un-install the app and remove my details from the Twitter section in the settings app and then log all in again and it still does not work. I have done this in several different ways including performing a soft reset on the phone and clearing out the cache and cookies in the phone and still it wont let me log in.

The one thing that I have noticed is that, on my iPad, it all worked OK, but in the Twitter section in the settings where you enter your details, above the line that has my user name in it has my name in it but it it greyed out. On my iPhone this section is grey but I am unable to enter my name and nor does it show up after I have logged in. I all so get a pop up message saying that either my username or password is wrong but it works OK on iPad.

I have added a screenshot of my error messages too.

Anybody had any issues like this I would be very greatful for any help or advice...

Thanks...