I don't know if this will help or not, but I thought the same thing when I got mine. My little one is about 3-4 months old now and I never even saw mine climb glass the whole time I have had it. Til about maybe a couple weeks ago, I saw him on the glass and moving very quickly I might add. Yours may be doing like what mine did, mine to this day never gets on the glass, mine will only be on the ground or in its plants. May be yours just doens't like the glass either: ) Have you tried putting yours on the glass at all, or have you just not seen yours on the glass? Doubt I helped at all, just thought I would share some insight on how mine is!