One additional hint I should mention that probably won't solve your problem but can cause odd/unexpected results: sometimes commands may depend on environment variables being set a particular way; but, contrary to what one might expect, cron may inherit a very different set (a changed PATH being the most obvious example). To mitigate this, variables can be set by placing variable declarations of the form ENVAR = VALUE (optionally enclosed with ') on separate lines.

Also, I noticed the man page on crontab mentions something about selinux security contexts potentially leading to unexpected results. This may explain the odd behavior under Aegis: http://unixhelp.ed.ac.uk/CGI/man-cgi?crontab+5