Damn, i've thought i sent RDD to a RED address on Cryptsy. Is is even possible to send to non existent address? It is very easy to confuse them on the current balance page on Cryptsy.
You should be extra carefull when sending and receiving crypto coins, cut paste can anytime go wired.
RED and RDD are very confusing too. But if the REDcoin address you used to transfer your REDDcoin is
not a valid REDDcoin address, then you have a chance to recover the already sent coins.
Thats only possible if you sent the REDDcoins from your qt wallet.
Recovering the coins from an online REDDcoin wallet or from any Exchange is not possible.
To recover, delete all the files from your Reddcoin home folder except the wallet.dat file.
Then, re-sync the blockchain(qt wallet). Your reddcoin will be back.
Normally it will take some days to get back your coin. Try your luck now.
Before doing anything don't forget to backup your wallet.dat