I got the hang of things just last night... It seems that I have to edit a player on my team
twice if I wanted to edit the player.T_T;; Both players.dbf and appearance dbf seems to have 2 instances of players in a dynasty team so the cause of the error seems to come from conflicting values.. I couldn't edit it with DB Commander though, so I had to use a hex editor... (I could edit it with a Notepad, but the files get corrupted it seems.

)
Thanks anyway.
