Can you clarify: Are you moving the slider to the "ON" position, and then you want it to move to the "OFF" position? If that's the case, it won't work because when in the ON position the Apex doesn't process any programming. Instead, change your code to this and then set the slider to "AUTO" so it runs the programming:
Set ON
When On > 005:00 Then OFF
You should also delete the Fallback OFF command because that only applies to physical outputs, not virtual outputs.
Also keep in mind, once the slider is in the OFF position due to the When timer, it will require you to move it back to AUTO to run again in the future. If you're wanting all of this to be 100% automated, it will require a different approach than the When timer. Let us know if that's what you're wanting to do.
