[WP 3.1.2] wp-admin in subdomain success, but subdomain web is mess

Hi, this is my first post and it is my first work with WP.

I follow the instruction step by step and can create subdomain successfully. Main web (knowupdate.com), main login and main admin is OK, no problem appear.

But, if I open subdomain web, in example: travelindonesia.knowupdate.com or its admin, something is not going right, it can’t load file in directory, example: http://travelindonesia.knowupdate.com/wp-content/themes/twentyten/style.css in example, but the post is appear.

When I open travelindonesia.knowupdate.com/wp-admin, everything is perfect.

What’s going on here? Any help I appreciate