Help with Holga film!

[Lia]

I just got a Holga 120 with flash, and took my first role of 120 400TX at 6x4.5, and should have been able to take 16 photos, but the numbers in the red window as I advanced the film only went up to 8. Does this make any sense to anyone? Heeelp.

[another view]

120 film will give you 15 or 16 shots of 6x4.5 and it shouldn't have stopped at 8. If you moved the slider next to the red window to the other setting (for 6x6) then you still should have 12 frames. It's really hard to move it, so it wouldn't have happened accidentally and even then it's still 12 shots...

The numbers can be hard to see thru the red window, but what happened at 8? Did the film just end? I'm confused...