Possible reasons why at may not run for you:

- HAVE you run ./configure ?  If that fails for some
  mysterious reasons, you can also do a

	make -f Makefile.old install

- You may not have a user or group 'at' on your system.

- If you find numerous 'try again' error messages in your syslog files,
  you have too many processes running; recompile your kernel for a
  larger number