SINGER Celine Dion has canceled more shows at Las Vegas’ Caesars Palace, citing a virus causing an inflammation of her vocal cords.Christi Nelson, an official with show producer AEG Live, said Tuesday that the French-Canadian pop superstar has been ordered to rest her voice for six to eight weeks and will resume performances June 9."I tried to sing at my sound check last week, and I had no control of my voice whatsoever,” Dion said in a statement. "We thought that after a few days’ rest I would improve, but it wasn’t getting any better.”The Las Vegas Strip casino spent $95 million building the Colosseum for Dion in 2003, complete with a humidifier to protect her voice.