"AT" command problem on IBM RT

[Wai-Keung Wong]

I am running AIX on IBM RT. Some of my users complain about the "at"
command. When they try to issue a number of jobs that start at same time 
using "at" command. They got some jobs never execute. I found the
problem is too many jobs being scheduled. I tried to duplicate the
problem, it seems to me more than five jobs start to have this problem
(not yet confirmed, I am still running some tests to test it out).
"Cron" try to reschedule jobs when one job is still running and the
other jobs should have started according to their scheduled  time. And
some how the jobs are not schedule well and state in the queue. Also I
found "at" may start two jobs at the same time ( I don't know whether this is
legitimate, but most of time "at" only invoke one job ) Have anyone
out there experienced this problem before and show me how to
solve it. Or does anybody know how "cron" reschedule jobs.

Thanks in advance.