Need some help with Cron

I’ve installed an ecard script that has the option to schedule cards to be send on a later date. Now in the somewhat incomplete manual it says I have to use cron to let lynx visit a certain php page.
Now when I add to my crontab the line:
12 0-23 * * * lynx -dump >/dev/null
Cron send me an email stating:“Your terminal lacks the ability to clear the screen or position the

(I added the “-dump” and “>/dev/null” on advise of a befriended programmer after a straight"lynx http://etc" gave me the same result.)

If I type this line at my command prompt I have no problems at all and it does exactly what I want.

Does anyone have any idea what I’m doing wrong here?
Any help would be greately appreciated!