This error occurs when you have reinstalled your MT4 Quantum Trading indicators in a terminal logged in to a new/different trading account. As you may already know, Quantum Trading indicators on MT4 can be used in one trading account at a time. Sometimes, a certain aspect of your current trading account changes which affects the indicator’s authentication process.
In any case, simply login to your account at http://enable.quantumtrading.com and go to your User Dashboard. Erase the current code in the Account Code field and click on the Update button. This will remove the old account code which would allow the indicators to bind itself anew to your MT4 trading account. After this you can go back to your terminal and and test if the error is resolved.