I would just give absolute dim levels a try. I mean, "set lamp to 100%" followed later by "set lamp to 65%". See if that always gives you 65%, or do you still get 0% occasionally.
If you still get 0%, then something is repeating dim commands. Ramping up, any extra brighten commands can't get past 100%. However, in ramping down, any extra dim commands will cause you to go past the target level, and continue until you hit 0%.