Check whether any of these conditions are causing the problem:
A user's administrative limit is set too low for the user's requirements.
The usage attribute is not being decayed. The administrator is responsible for ensuring that decays are performed on the device categories for all renewable resources (including the terminal device category). Typically, this would be done by regular execution of the limdaemon command. If a decay is not performed for a renewable resource, the usage attribute for that resource continues to increase until its limit is reached.
The decay period is too long. The frequency of execution of limdaemon should be set to accommodate the granularity of the shortest decay interval.
The decay attribute for a renewable resource is too small, or the interval attribute is too large. If the decay for a renewable resource over a given time interval is set below the typical consumption rate of that resource, the usage attribute will gradually increase until its limit is reached.