*Rihanna has reportedly cancelled two more shows on her concert tour — and the rumor is that it’s due to weak ticket sales.

The news follows reports last month that the singer scrapped her opening US show due to “production changes.”

Now, ticketing sites reveal that her scheduled stops in Denver on July 15 and Indiana on August 8 have been called off, with full refunds promised to ticket holders. Speculation among industry insiders is that Rihanna is suffering from an across the board drop in concert sales that have led many acts to cancel shows.

High-profile outings by the Eagles, the Jonas Brothers and the latest crop of American Idol finalists suffered poor sales. Christina Aguilera, Limp Bizkit and the Go-Gos’ canceled their tours, and organizers of the all-female Lilith Fair organizers said last week that they had scrapped about a third of the shows.

Promoters of Rihanna’s tour say she “hopes to make it up to them on the next tour.”