The subroutine get_seconds isn't being passed any parameters. It looks like what it wants is two strings, the first in the form DD/MM/YYYY and the second in the form HH:MI:SS.

Try calling it like so: get_seconds("01/01/2001", "12:00:00");

I mistrust all systematizers and avoid them. The will to a system shows a lack of integrity -- F. Nietzsche