Talk to Tully first.
Maybe go back to a saved game.
From walkthrough:
Go right to station west. See a snowmobile. Check-right click and see that Tully has the keys.
Take the rachet strap from the back of the snowmobile.
Go back to Tully at left and talk to him. Type in - snowmobile - left of the "suggest" on the frame.
Tully brings the snowmobile closer.
Use the rachet strap on the bear.
Take the rope from inventory. Click rope on cage pillar (above the open cage door); then click on strapped bear and lastly click on back end of snowmobile. The text should read: tie rope to strapped polar bear - cage pillar - snowmobile.
Automatically the bear is placed in the cage.
Claudia.