This error occurs when there is not sufficient CAD in your account in your chosen currency. If you are looking to withdraw CAD to your bank account, you must first have CAD in your Kraken account.
To see how much CAD is in your account, please click the currency pairs button in the upper left corner of any page on our platform for a list of pairs that can be selected. You can also select pairs in the intermediate and advanced order forms. Make sure you see this on the currency pairs button:
Then, go to your Account > Trade > Overview page to see how much CAD you have. Please note, the total row will display the total value in your account represented by the pair that you selected above. In this case, it shows total (valued in CAD) sum of all the currencies in your account.
If you do not have CAD in your account to withdraw, you will either have to trade the other available currencies in your account into CAD (you may have to trade into ETH or XBT before making a second trade to CAD). The alternative would be to deposit CAD into your account (How do I deposit CAD into my account?).