Can't see beacon light - why could that be?

I can't see the beacon light on one of the planes I am flying. Beacons work fine with all my other planes as well as with AI planes. I have checked the obvious and less obvious possible causes:- the plane has power- the beacon light switch is "ON"- hardware rendering is at max- I have the FX_2.bmp fileI am running some add-ons while flying: ASV (weather), FSNav, FSUIPC (latest version). Also, I have installed a number of add-on planes (PSS, PMDG, Aerosoft Commuter, iFDG) and numerous add-on sceneries. No FSPassengers.Could it be that any of these add-ons or that any hardware settings conflicts with my beacon? What are possible causes for beacons not to show? I have posted the same issue in the PMDG forum (I have it on one of their planes), but it isn't resolved yet. Since there is a larger audience on this forum, I was hoping for some hints thay may resolve the problem.ThanksChris