The problem is Memory card is locked. Slide lock to "Write" position. I have my card in the Write Position only eventhough it is showing the same

Hi there fellow Nikon user, I understand that you're having issues with your memory card. You mentioned that you already put on the unlock/write position but you;re getting the same error message. There's a big possibility that the card's locking mechanism is damaged. I suggest that you try a different memory card to isolate the problem. If inserting the other card doesn't fix the problem, Then most likely it's the card slot itself that is already busted. Have it checked right away by an authorized Nikon technician.
However if the other card was accepted and you're able to write info with it, then we can conclude that the memory that you're having problems with should be replaced.

Hope this help. Cheers!