As far as my understanding of MOC3021 optocoupler goes, it should latch pins 4 and 6 whenever there's a current flow between pins 1 and 3.
Image 1 - D1 not glowing and D2 glowing
Same happens on the breadboard except that even the LED between 4 and 6 isn't glowing either on the breadboard ( unlike the simulation ).
Image 2 - D2 not glowing and D1 glowing
Same happens on the breadboard
Update : Yes increasing current works out fine
Actually it's part of an arduino circuit in which I would be giving an output from an arduino pin to this, and there won't be any LED ( not white one for sure as I came to know now that it requires more voltage ).
So, perhaps it would be fine with an arduino pin, this was just to check the components before hand. Also , since MOC3021 has 15 mA forward current, so 5V would do the work ( as high in arduino pin would give 5V ). I suppose even 3.3V would do the work.
Thanks all .