There is always a CHANCE, but no guarantee, of course. The question might be whether or not it will cost you more than the $48 to take the time off of work and drive down to contest the parking cite.
And, are there other signs that indicate you have to pay for parking? Even if there is not such a sign at the entrance you used, if there are signs indicating that you must display a parking permit and these signs are present and legible in a place you could have reasonably viewed them, then you will likely lose.

