I'm trying to get my final Mini-kit canister from Episode V - Cloud City Trap (Chapter 5).

Here is the description of how to get this canister from a walkthrough I found:
Canister 6: At the room with the rotating lever and the vents (the second fight against Vader), crawl into the hatch.

None of the small characters (Wicket, etc..) will crawl through the hatch into the caged area.

Do I have to do anything special before being allowed to enter the hatch or have I come across a bug?
If it's a bug, has anyone else experienced this?