So I have a Yongnuo YN468-II that will not fire on a Canon Rebel 2000 (film camera).
What is strange is it will fire on a Canon Rebel T1i, and on a Canon AE-1 (another film camera).
It seems to detect focal length adjustments just fine and when I use an official Canon Speedlight that flash will fire.
I'm pretty sure it isn't a shutter speed issue as I've tried firing at 1/90 and 1/60 and I can put it in manual mode to test; however, even when in manual mode it won't fire.
If there are any ideas or more information that I can provide, please let me know!