what is 'LocationSubmission' ? I don't think it is a page? If it's not a page then it can't have a link. Try replacing the <% control ShowLocation %> with the the function I suggested so <% control GetLocations %>. This will return the child pages which are of 'Location' type so if you wanted each location to be listed then you need to make a page for each.
I think you are getting confused with what is and what isn't a page. If you want LocationSubmission to have a link it needs to have it's own LocationSubmission.php with a model and a controller extending Page and Page_Controller respectively. It also needs a template file LocationSubmission.ss.
Have a look through the tutorials to see how all this stuff works. http://doc.silverstripe.org/doku.php