No " no parking signs" and i get a ticket?

i was parked overngiht in city of walnut, CA. they gave me a ticket saying i violated their "no pakring on city streets from 2am to 4am"??? well their were no signs anywhere in the neiborhood saying anything about about parking. its not fair what can i do???? the city cant expect new poeple ping thro to know all their rules of unmarked streets