PHP Script not working

I have just installed Caldera's eDesktop 2.4 Linux. When I installed it,

Apache and PHP were also installed.

Now if I save a simple HTML page as .php3 it works. But if I save a page

with php script, it does not execute PHP script. Only html part is shown

and if I view the source of the page from the browser, I can even see
the PHP tags.

Can anyone help?

Thanks!