Communicate clearly to the user why indicator checkbox is inactive

[timlinux]

This should include visual language:

• make the text more faint

Information que's

• Provide a tooltip or other means to tell the user why it cannot be activeated e.g. ' There is no data for for this time period. Select a different time period or ask your administrator to change the aggregation rules to show the last recorded values.'

[meomancer]

This has been implemented