Paired Tempest beltpacks won't register quickly or won't register at all with it's paired base station.  Check for the following:
Another Tempest base station may be in use in close proximity that is using a similar lock out and network number to the system having the problem.  It is advisable to do the following to resolve the problem, set the network number to be at least 4 units away from the other base, that is if one base's network number is 4, set the network number on the other base to 8 or higher.  A total of 63 network numbers are available.
Changing the lockout number is also advisable so that another systems beltpacks can't accidently log on to your system.  There are 255 different lock out codes available. 
Systems shipped from the factory are defaulted to network number 00 and lockout code 255.  It is advisable to set them to some random pattern of numbers to avoid interference issues with another Tempest system.