by Ken Task.
Maybe I'm mis-understanding, but it sounds like you are trying to use the LTI External Tool to the Provider on the same server. Is that correct?
Might not be able to use External tool and link to the Provider on the same server.
Here's one to 'play with':
http://elearn.tcea.org/local/ltiprovider/tool.php?id=1
Consumer key: e00f6c053bfd358d29fc3738baf53474
'spirit of sharing', Ken