I haven't personally had a problem, but the shore power inlet is fairly cheap and super-easy to replace, so I'd start with that if you aren't getting any reading on the inside of the connector.
I replaced mine with a Furrion 30-amp inlet from the Sportsmobile Store. They had the best price on it, even compared with Amazon, at the time I bought it. It's $18 at http://www.sportsmobilestore.com/furrio ... amp-inlet/
The Furrion inlet is nice because it has an LED that lights up to show that you have power coming in. I matched it with a new Furrion 30-amp cord, which also has an indicator light to show that the cord is getting power. Fairly handy to have IMO. Very easy to replace.