My question involves a traffic ticket from the state of: CA

I have a question, please any help will be appreciated!
I am employed as a live-out nanny for this woman who lives in a condo complex. Now to enter the complex, you must turn right at the corner and proceed up the hill. (That is the only entrance to her complex, there is no other entry). Now since the complex entrance is also located right off a major freeway, many people previously used the entrance to make illegal U-Turns after turning right into the entrance, thus disrupting the road. In other words, they would come off the freeway, make a right turn into the complex, then instead of going up the hill where the condos are, they would just make an illegal u-turn and go back on the freeway. The residents lobbied the city and a sign is there, saying NO RIGHT TURN 7-9AM, MON-FRI. Well my boss had told me why the sign was there and said that residents and guests/visitors could enter, she told me to just tell the cop (if there was one) that I was an employee of a resident in the complex. Well one morning, right after I made the turn into the complex, I was stopped and cited. I told the officer I was entering the complex to go to work, not to make a u-turn (which is why the signs are posted) and that I was a domestic employer. He asked for proof, and I didn't have any on me, so I was cited....$168.00. I am guessing the officer had heard many stories from others and couldn't tell if I was lying or not.

Anyway, I want to contest the ticket. I did make the right turn, I admit I did. However, the sign is posted with the intent to cite those who make illegal u-turns, not to cite a person going into the complex as a visitor or resident. I sent a copy of my paycheck from the day I was cited, with my employer's name/address clearly on the check to prove I had a legitimate reason to enter since I was going to work.
But are there exceptions to the rule? If a sign is intended to prevent certain activity from occurring, yet the intent of the violator was not to engage in such activity and the person cited has proof that they were there legitimately, do I have a case?

For the record, I have a 6 1/2 perfect driving record.
Sorry so long, but I just wanted to be as clear as possible.

I would appreciate your help on this. Right now, I am waiting on an answer for a trial by declaration, but don't know if I have a chance at winning!