Thanks, but tried that already, only works once

I leave my PC running 24/7 - wants to show "EVERY 12" hours but not once.

Know what I mean?

Here's my code what I thought it should works.

/timer 12:00 1 0 echo -a It's now 12 o clock.

See the interval 0 - that's unlimited right? - how come that doesn't work?