Actor-comedian Bernie Mac, who died this summer, was a funny guy, and often the lone bright spot in an otherwise clunky comedy. That makes this by-the-numbers, buddy-trip comedy from Malcolm D. Lee doubly disappointing. One, Mac deserves a better swan song, and two, how can you take such great source material -- a trio of feuding 1960s and early '70s R&B performers -- and make it so lackluster? There is an encyclopedia of real-life histrionics and hi-jinks to draw from; filmmakers could have asked the late Isaac Hayes, who makes a cameo here, for backstage details. Mac and the capable Samuel L. Jackson do their best to liven up hackneyed plot devices, but even these two fuse-blowers get tripped up in the gooey muck of pointless sentimentality. Too bad -- Mac should have left us laughing.