With any luck, the 65-year-old Reitman said someday they'll be able to bust ghosts together again.

"He's a huge gift to most every movie he's in, and he's been huge gift to my life in the five movies we did together. I'm extraordinarily appreciative," Reitman said. "He's grown cantankerous as he grown older, and he's always been fussy about the movies he'll make."

"There's an enormous amount of pressure on he and I with regards to movies like 'Ghostbusters III,'" Reitman added. "People want to know why (he doesn't want to do it), but I feel like he's earned the right to do whatever he wants. I'm very happy with how I've been able to work with him."