Sub Domain Question

[Esquilache]

I have created 2 sub domains but for some odd reason when I go to subforum.website.com I don't get anything but when I go to website.com/subforum I can see it.

Why is this happening?

 

[descalzo]

Got URL?

 

[Esquilache]

http://forum.tacticalnuclearpenguin.org/
&
http://support.tacticalnuclearpenguin.org/

I don't understand... I can see them if I go tto http://www.tacticalnuclearpenguin.org/forum/ or to http://www.tacticalnuclearpenguin.org/support/