Grammy-winning R&B singer R. Kelly, 35, pleaded not guilty in a Chicago courtroom on Wednesday to 21 counts of child pornography stemming from a videotape he allegedly made with an underage girl, reports CNN. Kelly (whose full name is Robert Kelly) wore a conservative blue business suit and red tie to the brief hearing, says the news network, noting that he waved to dozens of supporters outside Cook County Circuit Court. Kelly, who remains free on bond since his June 5 arrest, is due back in court on Aug. 7 for a discovery hearing. If convicted, he could face a maximum of 15 years behind bars on charges of videotaping, producing or soliciting for child pornography, according to the grand jury in the case. The star, perhaps best known for his song "I Believe I Can Fly," released a song early last week in which he blames his troubles on being famous. As PEOPLE.com reported, his record label provided an advance copy of the single, called "Heaven, I Need a Hug," to Chicago station WGCI-FM, which has been supportive of him during his recent troubles.