Photos and Videos
Getty Images for NARAS
Singer Rihanna performs onstage during the 55th Annual Grammy Awards on February 10, 2013 in Los Angeles, California.
Rihanna is apparently too sick to sing again.
Live Nation announced that Monday night's show in Houston will not go on "as a result of illness," but the concert promoter stated that people should hang on to their tickets so that they can be honored at a later date.
Rihanna previously missed two dates on her Diamonds World Tour in March due to laryngitis.
There's been no explanation from Ri-Ri yet, the only tweeted missive today being a happy birthday message to her brother Rajad.
She reportedly attended a pal's birthday party at Marquee in Las Vegas on Friday, along with opening act A$AP Rocky and Snoop Lion.
Rihanna's tour is supposed to touch down in Dallas tomorrow.