Cannot log in

TakkookkaT

Recently I started playing on many of my old accounts again, but only today did I realize that despite being able to play on them, I can't access the website with 3 of them. I'm 100% sure that I typed the ID and password right and still, it says they are wrong. Also, there is one with which I'm able to log in, but can't post on the forum.
The only one that I have no issues with is this one.

I'm also 100% sure I have never broke the rules on any of my accounts.
Could this be a simple error or something else is causing the problem?

TakkookkaT

Is there noone who could help?
I'm not exactly asking for a solution. I'm just inquiring about possible causes.

I know that with a banned account you cannot log in to the game while you are still able to log in on the website, but I've never heard of the opposite.