distribution of this film
It seems to me that this movie wasn't distributed through normal channels when it first came out. The advertising looked odd, as if the movie was some sort of special event at whatever theater was showing it. A friend told me that this was indeed the case, that the movie's promoters simply rented the theater and showed it over the course of several days, paying the theater owner a flat rate and retaining the ticket proceeds for themselves. I don't know much more about it, except that this sort of thing seemed to be done with movies that have questionable marketability.
I believe that the makers of 'In Search of Noah's Ark' did the same thing. Perhaps 'You Light Up My Life' was promoted among church-goers.