quoting the kcron manual...

To run a scheduled task immediately, first select the task. Then select Edit->Run Now

Unfortunately "Run" is deactivated, even when I run kcron from gksudo.

Any ideas how to enable it?
Alan
(Hardy)

This is likely due to a system configuration issue. As the software is not shipped with KDE, I do not know much about it. Please contact the developer of that software, who will likely know exactly why it is disabled.