Cryptsy, one of the biggest altcoin cryptocurrency exchanges has experienced withdrawal and other problems for a long time. If you are not a complete crypto-novice there is a high probability you have gone through, heard of or read about their strange behaviour towards customers (see here, here, here or here and here). Cointelegraph have sent some questions by e-mail but without any response.
Here are just a few complaints published on forums about a year ago...:
http://cointelegraph.com/news/115981/is-cryptsy-the-next-mtgox