That Dave Lee Roth didn't show up because he wanted to perform "Jump" and Velvet Revolver had practiced You Really Got Me.
According to AP:
''We offered him opportunities to play and sing a Van Halen song of his choice with our house band, including his own guitar player, or a song with Velvet Revolver, and he refused those opportunities,'' said Joel Peresman, president and CEO of the Rock and Roll Hall of Fame. ''We made every effort and the decision not to come was solely his, not ours.''
THAT'S the Diamond Dave, I know and love.