Here are some tips for the pin trading event.
Make sure that the pin you want to trade is a series pin (Tiki, Food, Hotel, etc). It had to have a value of 500 credits when you purchased it. Any other pins such as quest pins or pins sold less than 500 credits will not be acceptable in the trade events.
Also, please try to keep conversation with the Staff at a minimum - the trading will take longer and there is nothing like dcing right when you see that pin in the trade box.
Good Luck and have fun.