Remember you can always use an old address if needed. (not a good idea at all for security reasons) but one time (Not on silk road) I copied and pasted the wrong number in, Luckily, it was an old number that I used for Mt. gox.. So it got there. No need to worry, and also remember there has to be 6 confirmations before it will show up. I have seen 6 take as little as about 1/2 hour to a couple hours. Thats why I always use a wallet. you can see it when it reaches the 6 mark.... Dont ever just transfer from exchanger to SR.. (if you did, just dont do it again)