Why was there never a 3rd movie?

I have mentioned this on the Maggie Smith boards, but I will mention it here as well just for curiosity sake. In late 1995 a script was written and production was being set up for "Sister Act 3: Breaking the Habit". It was reported in national newspapers and there were stories circulating that Whoopi Goldberg had surprisingly signed on for the film quite quickly. However other recurrent cast members were reluctant to sign up - Maggie Smith included, who thought the script was too similar to the first film and made the Mother Superior character into a "b**ch" like she was in the first film. Kathy Najimy was also reluctant to return, and instead of recasting the roles the film was put on hold for a year and then finally dropped. As to the actual plot it is unknown and probably will never be known unless someone finds a copy of the script.