Raoming profiles on laptops

I use roaming profiles on my NT4.0 network. All the workstations are Win 2000. I just purchased a few laptops with docking station. When the laptops are on the docking stations here at work there is no problem with profiles. When a user undocks and takes the laptop home and logs on to the laptop it uses the cached profile. When the user comes back to the office, docks the laptop and tries to log on his roaming profile is not loaded. Any ideas?