What's missing from this picture?

This has always puzzled me, and I'm sure there's more to it than meets the eye. Mack Sennett released this publicity photo of new star Harry Langdon in or around 1924. Harry is seen outside his dressing room, contemplating a signboard featuring the names of Sennett performers who had previously used the room, illustrating his status as new top dog in the Sennett pantheon. Of course it's just a gimmick, but the names Sennett or his publicity men opted to use are somewhat peculiar. Chaplin is a given, and his half-brother Syd was a star at the time. Gloria Swanson is also an obvious inclusion, although I doubt she would have wanted her name memorialized as a Sennett discovery. Harold Lloyd, on the other hand, breezed through the studio between gigs for Hal Roach, barely registering as more than an extra, hardly a Sennett "find". And what about the names that aren't included? Roscoe Arbuckle is missing, undoubtedly because of the scandal and blacklist, but what about Mabel Normand?? Given Mack's on again/off again relationship with Mabel, this seems a rather pointed omission. And that her star was on the decline in 1924 was no excuse. Hell, they've got Ford Sterling's name up there! Strangely, if you look closely at the photo, you'll notice that room was left at the bottom for Langdon's name, but one name on the sign was painted over in white and Langdon's name was written over it. Was it Arbuckle? Mabel?