– Queen Latifah has not been a force on the hip-hop charts in years, she’s box-office poison on the big screen and is reeling from two failed talk shows. But the woman has not lost her swagger.

In the opening scenes for “Bessie,” a long-awaited bio-pic of 1920s-30s blues sensation Bessie Smith that premieres Saturday on HBO, Latifah struts her stuff like she’s Beyoncé, Barbra Streisand and Britney Spears all rolled into one toxic package.

If only the movie could swing with equal confidence.

Despite Latifah’s gallant efforts, writer/director Dee Rees tones down the singer’s amazing career, providing viewers a somewhat flat-noted version of what was certainly a full-throated career.

Perhaps the producers never really grasped the heartbreak embodied in early blues music. It’s a dilemma the script (adapted from a story by Rees and Horton Foote) hints at in a scene involving Bessie’s future mentor, Ma Rainey (played by Oscar winner Mo’Nique), who chastises Bessie for not being “black” and soulful enough to become part of her troupe.

Latifah had to learn that lesson for herself, in fact. She admits that when she was first approached about the role more than 20 years ago, she was too focused on rap to fathom the power of the blues.

“When this project first came my way, I didn’t think I have had the life journey that went along with what Bessie had gone through,” said Latifah, who admitted she had never even heard of the blues legend when she was in her 20s. “I could have played her then and done a great job, but through my life experience, I’ve got to live more of the blues.

“For her to command a room, a room with no audio equipment, and blow out everybody in the back of the room — I mean, [the music] may be a hundred years old, but it has a power that a lot of artists could learn from today. If there was a Bessie Smith out there right now, she’d blow everybody out of the water today.”

History backs up Latifah’s boast; the film doesn’t.

There are certain musical moments that capture the tenor of the time, particularly when Rainey and Bess set aside their popular standards and face the cold hard facts: sexism, poverty, stingy managers and, of course, racism.

“The blues really became the first way that people could begin to talk about these issues and make them personal,” Rees said.

That may be the case, but “Bessie” spends more time showing the singer threatening lovers, cutting up suitors and lambasting auditioners than she does demonstrating how the power of her voice could change the world. While the musical performances are impressive, they don’t convey a sense of the troubled times.

Consider this a decent night of karaoke, and little more.