Sometime Idex exchange went to mantainance action and in this time, you could not buy or sell anything. Remember that Idex is decentralized exchange, you should not directly add your wallet with private key to it, lets use metamask to protect your wallet for scammers.
Thanks for the information as I about to do some transaction at Idex and I don't know what to do about this exchanges. I will buy first my matamask wallet for this.