Aspiring R&B diva Christina Milian is singing the blues.

I hear that Island Def Jam dumped the 24-year-old Milian — best known for her 2001 single “AM to PM” — after her third album, “So Amazin,’ ” was less than amazin’ in the sales department.

Adding insult to injury, I’m told that Vibe magazine canceled Milian’s scheduled August cover — after Island Def Jam informed the mag that she’s toast — and replaced her with R&B singer Keyshia Cole.

Milian’s PR rep confirmed the split with the record label, but tried to give it a sweet sound: “Christina Milian and Island Def Jam have decided to end their relationship due to creative differences. This was a mutual decision.”

Island Def Jam had no comment.

But I hear that Milian — who a few months ago antagonized her ex-flame, MTV “Wild ‘N Out” star Nick Cannon, by dissing him in interviews and a song — also irked record execs by refusing to take direction from Island Def Jam CEO L.A. Reid.

Despite Reid’s pleading, I’m told, Milian passed on recording “S.O.S. (Rescue Me),” which ended up becoming a hit single for her label mate Rihanna — whose record, “Girl Like Me,” sold 115,000 copies in its first week.

By contrast, Milian’s heavily hyped album sold fewer than half that number — a meager 50,202 units — in the week after its May 16 release. Never mind that Island Def Jam laid on a promotional budget worthy of Mariah Carey.

I’m told folks at Island Def Jam are blaming Milian’s boyfriend and executive producer, Marcello (Dre) Valenzano, of the producing team Cool & Dre, for the artist’s alleged lack of cooperation.

Milian’s flack didn’t address the boyfriend flap or the Vibe cancellation, and Vibe reps didn’t respond to a detailed message.

Credit: NY Daily News