no mystery really. in the init.sqs file i add an eventhandler thus -
badguy AddEventHandler ["killed", {player setcaptive true; _this exec "badguy_nomore.sqs"}]
the setcaptive command is just to prevent surrounding loons popping the player while the badguy-dying cutscene in 'badguy_nomore.sqs' is playing.
i just have to check one thing... nope. there is a variable upon which the script depends, but the one and only way it could be triggered wasn't active.
it's not just the badguy either. there's a kidnap victim in there with a 'killed' event handler, and in my annoyance at having killed the badguy with no effect, i popped the kidnapee too, with no result.
most annoying. :-\
EDIT - found the problem. the variable was set in another script, disabling the eventhandler... my bad... sorry