[FUNExtreme]

Do you set the variable to 0 when the player connects. If not, it could be possible that for example: Player 1 with level 5 admin is in the server, that player then leaves and someone else comes in with the same playerid. That new player will then have level 5 because it wasn't reset.
Schematic:
Player 1 (ID: 0) (Level 5 admin)
Player 1 (ID: 0) leaves
Player 2 (ID: 0) joins
Player 2 (ID: 0) (Is level 5 admin because it wasn't reset from Player 1)

If that isn't the problem, I'll look a little more into your script