Stopped by the police in France

At 1 minute and 21 seconds, I entered into a car park. Unfortunately I entered via an apparent no entrance. The police were waiting and issued me with a 130 Euro fine. I was gutted!!!!!!!!! I forgot my camera was running however you can hear the conversation I was having with the police officer. The 'no entrance' sign is not pointing towards the direction of travel... if you slow the video down, you can see that it is pointing in the wrong direction. So how was I to know that it was a no entrance? You can hear the police officer admitting that the sign is placed in the wrong direction and that she is going to speak to the mayor to get in changed. The thing is, that in the 20 or so minutes I was held there, at least 10 other vehicles (All French vehicles) all committed the same mistake I did... all issued with 130 Euro fines. The police officer also admitted that she had issued 14 fines to other drivers earlier in the day and she admitted to my riding colleague, that the previous day, 41 fines were issued. If you do take the time to watch this video, or even the clip, then let me know your thoughts. Do I have a case to appeal the fine?