Just send it to a MEW (my Ether Wallet) first and then send it to the exchange.
https://www.myetherwallet.com/ A lot of exchanges don't accept smart contract payments. Bittrex, Bitfinex, Coinexchange.io, Coinhako, Coinpayments, Cryptopia, Exodus, Koinex, Ledger, Liqui, SimplexFX all don't accept smart contracts
It has to do with how it is processed on the blockchain.
On the blockchain the transaction is to the contract address and the funds are sent to the receiving address via an internal transaction (as data).
Normal Transaction:
Contract (Internal transaction)