sometimes you just have to cut your losses
 
When I asked him why his coworkers felt he did not respect them, he grunted, "Because they are all fools!" This comment should have been a hint.
 
Buddhist and consultant Marshall Goldsmith writes in Fast Company an article recommending that those of us who are leaders focus our efforts on the people who respond and not on the people who don't. 

I really believe this.  Just finished reading First Break all the Rules by Marcus Buckingham where he basically advocates the same thing.  I also believe it's biblical.  Through the gospels we see Jesus giving people open doors to respond to Himself.  But if they walked away, they walked away.  He seems to have done this with the rich young ruler.  In those instances we are, as it were, a fragrance of death unto death, but we are still a fragrance.

All we can do is to give people open doors.  We cannot make them walk through them and we shouldn't try.