Cannot set trigger to check for existing files

[stripecat]

Hi

I tried to create a trigger with this expression:
{Template OS Linux:vfs.file.exists[/var/run/reboot-required].last()}=1

It's supposed to raise a warning when Debian/Ubuntu-server should be rebooted.

But I get this error when I try to create the trigger: "ERROR: Cannot add trigger".

Any ideas?

Regards
Erik

[Atsushi]

Are you added item that have key vfs.file.exists[/var/run/reboot-required]?
Or, error message was not output to the other?