Bad dialogue: aka, your people need to talk like people, and they need to have different personalities.
No chemistry between characters: And I don't mean romantic chemistry. Every character should vibe with eachother in an entertaining way because of their differences and commonalities. Otherwise...why are you spending hours drawing them?
There is no acting in the way the comic is drawn. Exaggerate your emotion, have some fun, make them move around the scene in the way an actor would if they were in a play. They shouldn't be standing there still faced for 10 minutes.
There is no fun to your paneling. Even Calvin and Hobbes, which was a gag comic, had a lot of fun in their paneling. Mix it up. Have some fun. It's a comic.
You forgot to write a hook early enough in your story (and I mean hook me in by the 2nd episode), or your hook just doesn't hook me enough.
Grand abuse of white space. You ain't fooling no-body, 60000 px of white space doesn't count as the passing of time. Replace that white space with a fun stamp of like...leaves or something. Maybe a gradient of the sky. Literally anything but eons of white space unless for some reason we have ascended into the sun.
