The bulbs are incandescent. The codes are set to B 15. I do have a motion sensor for some other lights, which are on B 16. I'm not using AHP, just the keychain remote.
After re-reading this thread a few times, I want to make sure I understand your setup correctly:
A. Porch light on B15 (single XPS3 switch)
B. Entry light on B15 (XPS3 with companion XPSS 3-way setup)
C. Motion sensor on B16 for other lights.
D. When turning the switches on or off manually (at the XPS3 switch), both function correctly.
E. The XPSS can only turn the lights off - it is unable to turn the lights on.
F. When using the keychain remote to turn on the lights, the porch one works fine, but at the same time the entry one (on the same B-15 code) flashes three times, then turns off.
Assuming this is all correct, I've got a few more questions (I know it is a lot, but I really want to try and understand the problem so I can try to help):
1. If the lights are both on, does the remote work to properly turn them both off at the same time?
2. If you pull the "bulb change disconnect" switch from the porch light switch (so it won't turn on at all), does the entry light behave the same way?
3. Did you try disconnecting the "control wire" from the XPS3 (as Brian had suggested)? If so, did that make a difference?
4. When you "tried other channels," did you change the house code, unit code, or both?
5. When you "tried other channels," did you only change the one switch that is acting up, or did you do both switches? Did you change any other switches at the same time, too?
6. Is the motion sensor located near either the porch light or the entry light (the lights themselves, not the switches)?
7. Do you have any other devices on address B15?
--Noam