I don't think they'll illuminate in daylight; it needs to be dark.
I don't have them on my current car but did have them on my mk6 Golf and they'd light up when it was dark and under the following conditions;
- if in the car; when opening the door to get out of the car
- if outside the car; when unlocking the car via the remote (don't know what happens if you've got keyless).
Presumably there's a section in the manual outlining how and when they work on the mk7.5?