u/Common-Ad8362

Today I received a 35€ fine for “Schijf ongeldig of onleesbaar”. I had parked in an area where I am allowed to stay up to two hours by using the parking disc. Above is the picture that they uploaded as a proof of my disc being “unreadable or invalid”. Can someone explain me what was wrong or why I was fined? Also what chances are there that I can successfully contest it? Thank you in advance for any help!