In Carrom Disc Pool there is a feature that allows the player to claim free rewards by simply watching video ads. However, if this option is greyed out and not possible for you to press the button to watch the video, it means that there are no ads available at that given time.
The only way to claim these rewards if that happens is to wait until new ads become available.
This is something external to Miniclip and that we have no control over.
It might take hours or days for these ads to become available.