A very simple question

I enabled multisite on one of my blog (abhilakshya.com)(fresh installed) and infact added subdomain (pics.abhilakshya.com) as new site. I followed all the procedure mentioned at http://codex.ww.wp.xz.cn/Create_A_Network.

but whenever I want to use http://pics.abhilakshya.com/ it is giving me 500 error. Do I have to install a separate wordpress on http://pics.abhilakshya.com/

How http://pics.abhilakshya.com/ will use different database instead of one which is used by abhilakshya.com?