Luar,
Do you have a CAD worker configured (either a remote CAD Worker or local to the Windchill server) to perform the publishing within Windchill? Check Site > Utilities > Worker Agent Administration. If all you see is a blank list or a worker named "triumph" then you don't have any workers configured. In that case, the only way publishing will happen is if you do a custom check in and select to do client-side publishing (i.e. "check in Models and Viewables" option or just the "Viewables" option).