Panel 1: We see Connie in the audience as Phil and his band (The Warthog Good Times Boogie Band) perform a set of music that Elly-can't-sing-along-to-and-is-thus-not
Panel 2: She then thought-bubbles "If he sees me, I'll die" like the good little freaked-out teenager she is.
Panel 3: As he accepts the audience's applause, she thought-bubbles "If he sees me, I'll go nuts! I'll get up and leave!"
Panel 4: We focus in on her frowning face as she starts to panic about something else; she tells us what this new fear is by thought-bubbling "Why hasn't he seen me??"
Summary: There could be many reasons for this. First, he wasn't expecting to. Second, it's a darkened club so she's simply another roundish face with glasses. Third, and this is the clincher, even if he had expected her and was looking out for her, she sort of blends in with the crowd pretty good. This sort of makes her hope that by some sort of magic that their eyes would meet leading to her odd little dreams coming true pathetically misplaced.