Cant get protected content message to show

I've seen other threads about this but not found a solution yet.

I'm building a site which has most of the content available to anyone (stranger level set as Free members) but with three levels of membership for some content.

I've set a page called No Access for wwhen anyone tries to reach protected content - this page includes a link to the joining page.

When I make the site members only I get the correct NO Access message. However, when I have membership enabled but allow the free member access, if I try to reach a page outside that level of membership I simply get the default 404 notice.

I don'#t want to change the 404 - I want that to show for non existent pages - but equally I really need the No Access message so people at the wrogn membership level are alerted and given the option to upgraade.

Please help!

If you go to http://www.socialmediashop.co.uk/join/members-level-1/ you will see the 404 message. Go to http://www.socialmediashop.co.uk/no-access/ for the content it should be showing!