Mail() function not working

HI all,
I am trying to get an automatic mailout to be sent when a certain php page is loaded.

The synatx i am using is:
mail("bradwright@mydomain.com.au", "worked", "Line 1\nLine 2\nLine 3", "admin@mydomain.com.au");

I am running ES 4.1.2

I get no result when page loaded...no error message, no nothing.
when i go to my mail logs, nothing there.. no requests,denies anything that corresponds to the time and date the mail should go out (ie when i load the page).

Hope someone can help, where should i be looking??

Thanks in advance
Brad Wright