As a user, I want to be informed by a short text message that the feature I am trying to use is not available for X reason.
Example : I tried to select a segment on a report (key metrics) running on a rollup report suite. I couldn't know/ remember/ spent time to read the help section/... so I wasted my time and the one of Adobe Customer Care people to get the simple answer : segments are not available for rollup report suite. A simple text message close to the feature position ("segments are not available for rollups") would have helped a lot and spare time to many people. Instead of that there was a blank space which is confusing for a user, and let me believe it was a bug....