[mrtg] MRTG not updating RRD files

[Dean, Mike]

I've been running MRTG on two separate systems with each running the
config files for systems that were local to their network.  Yesterday, I
moved everything to a single system and all device RRD files are being
updated as they should except for one set of files.  Regardless of what
I do, the RRD files will no be updated by MRTG.  MRTG is running and is
no giving any system errors, and running any of the configuration files
by themselves (non daemon) does not produce any errors either.

All of the systems are being updated via a DS3 WAN connection that runs
at about 10mbps (plenty of room left) and two of the devices in question
are Catalyst 6513s with more than 200 interfaces each.  

If I remove the RRD files, MRTG will create new ones; however, after
their initial creation, the RRD files never get updated.  All other
devices, including other devices being updated over the same DS3 are
being updated correctly.

System Information

Mandrake Linux (kernel 2.4.22-10mdk)
MRTG, v2.15.0 
RRDTool, v1.2.11
Frontend: routers.cgi, v2.16

Thanks, in advance!

Mike