Only when disk tray is closed I have '' An error has occurred ''

My gamecube is booting fine, but if i have my disk tray closed or when a small sound coming from the disk reader ( still with the disk tray closed ) it will show me a red error message with the text : An error has occurred. Turn the Power Off and check the Nintendo GameCube Instruction Booklet for further instructions fix

I tried to boot the gamecube with the disk tray open, i don't have the small startup sound with the animation, it just shows gamecube, then it goes to the main menu. If i do this and then close my disk tray the error is coming back and i have to restart my gamecube.

It do exactly the same with a game.

I don't really understand what is happening, i checked the potentiometer ( it's between 150-250 ohm ) and my lens is not dirty or anything. This is really related to the disk tray and i don't get what could be the problem here. Probably the disk reader but where and what cause this ?

If someone have an answer at least to understand what is happening here it would be really nice.

Thanks