A Trans States Airlines Embraer ERJ-145 on behalf of United Airlines, flight AX-8084/UA-8084 from Chicago O'Hare,IL to Syracuse,NY (USA) with 33 passengers and 3 crew, was on approach to Syracuse when the crew declared an emergency, reporting the #2 engine's anti-ice system was not working. When the aircraft broke out of the clouds descending through about 2300 feet, they cancelled the emergency, reporting they had not picked up any ice. They continued for a safe landing on runway 28.