dimmer con bt137
then what is your prob,
it should be , when the lamp is not there, the terminal is open there is no connection between phase and neutral.
and when you connect the lamp ,a connection is there , so whatever be the fired angle after that you should get the remaining cycle of that ac wave.
from w/f it is clear that the , lamp is bright and there is no dimmer action in it ...yes.
remove R23 , and use R20 = 24 KOHEM , replace your opto triac , it is damage ...too.