Multisite cannot find module in sites/default
So this was the issue,

When I created the sub-domain i used cpanel, even though I specified

/home/&lt;username&gt;/&lt;subdomain-name&gt;

as the home directory path,

it would override it in the vhost entry to: 

/home/&lt;username&gt;/public_html/&lt;subdomain-name&gt;

so,  even though I created the symlink at the right place, it never hit it, 
so when I went to the subdomain url is was picked up by the drupal htaccess as a url to the live site

lots of confusion and lots of annoying behaviours

As soon as I edited the vhost entry to the corect path, everything worked correctly

thanks for all the reads though

Jim