[rancid] rancid running from cron fails for some devices that can be manually run

[Peter]

HI All,
	I was wondering if anyone has seen an issue like this before. I have  
rancid setup at my work to nightly backup a bunch of cisco routers ,  
switches and 2 F5 load balancers.  I have it set so it's a cron job  
that runs at midnight. Every night when Rancid runs it fails for the  
F5's and succeeds for everything else. What is weird is that if I  
manually run rancid against these devices individually or as the full  
group they succeed. I have tried moving the cron job to a different  
time and also verified that connectivity has not been lost during the  
time it runs. The only constant I have found it that if rancid runs  
from cron it fails for these 2 devices and it succeeds if I run it  
manually.
Has anyone ever seen similar behavior or have any thoughts ?

thanks,

Peter