If you have enabled Whitelist on your account, you are able to withdraw your funds only to the addresses added to Whitelist.
Here are three possible solutions to this problem:
1. When you see this error, first make sure that destination address matches exactly the address added to your Whitelist. Upper/lower case letters matter as well.
2. Second, please keep in mind that you need to whitelist an address for each coin or token separately. So in case you have whitelisted some address for ETH withdrawals, you will not be able to withdraw a token to this address. You need to whitelist it for this specific token as well.
3. Probably you have whitelisted the address, but additionally to this address, you are using a Payment id (destination tag, message, etc.) when trying to initiate a withdrawal. The system will not let you do this. Payment id is an identifier of the destination where your coins will be sent. So you need to whitelist this payment id together with the address, using the special field.
Important: After adding a new address/payment id to your Whitelist, all withdrawals will be suspended on your account for 48 hours. You will see a notification about it on your Account page. This is a security measure for your funds' safety.