Why no "9 Chickwood Lane" collections?

Every other comic strip has multiple collections available. You can’t turn around without finding another miserable “Garfield” volume. So why has “9 Chickweed Lane” gone on so long, through so many changes, and not a single collection issued? Anybody know anything about this that isn’t just a random guess?

Umm…cause there is a collection?



Oh, & here is his Pibgorn collection.


That one doesn’t count. It only involves Solange, and not much of her. The main storylines have never been released in any collections, AFAICT.