Use this solution
I also facing same problem
Warning: include(/test/assets/header.php) [function.include]: failed to open stream: No such file or directory
Warning: include() [function.include]: Failed opening '/test/assets/header.php' for inclusion (include_path='.:/usr/local/lib/php:/usr/local/php5/lib/pear')
But I solve them after searching it on google in 2 dyas.
Solution:
you have to define your path then use include function as blow:
define (DOC_ROOT_PATH, $_SERVER['DOCUMENT_ROOT'].'/');
you can use any directory structure after that.