When the Dashboard sends a switch change message to the device, it can take a little time for the device to respond to indicate the change has been effected. While this is happening, the Dashboard will show the switch as disabled (and show a “spinner” indicating that it is waiting).
There are some rare circumstances where this state can be triggered due to the switch state being different to expected when the Dashboard first displays the Switches tab. If you see this when you first access the Switches tab, allow up to 90 seconds. If the button is still disabled after this time, please contact Wattwatchers support.