Rihanna has scrapped another show as she battles to recover from illness. The Umbrella singer hopes to reschedule her Monday night (15Apr13) concert at the Toyota Center in Houston, Texas. A statement from concert promoters Live Nation reads, "Unfortunately, as a result of illness Rihanna is unable to perform this evening at Houston's Toyota Center. Fans are instructed to retain their tickets to this event pending rescheduled show date information." Shows in Maryland and Massachusetts were cancelled last month (Mar13), when Rihanna fell ill. At press time, her concert in Dallas, Texas on Tuesday (16Apr13) is still scheduled.