Sub_domain not working

[Computerama]

I am good at trouble shooting and finding problems but when it comes to fixing I need some help. So Using vhost modification in apache config? I am not sure how to. All I know when a sub_domain is created it adds some lines that apache will error out on the line looks like this.

This one is incorrect and stops apache
ErrorDocument 403 (2) /_errorpages/403 (2).html

This one is correct.
ErrorDocument 403 /_errorpages/403.html

All I know how to do is edit the main vhost file witch will fix the problem until it is rewritten.