I created a LTI tool provider and registered in Canvas of Princeton. It works until I have changed the launch link(I have accidentally had a typo in the launch link.). I found out the typo and tried to correct it by deleting the app(admin panel->settings->apps) and added it back with the correct launch link, but the oauth_signature_base_string still shows the wrong link as in red: (The link with the typo just can't be correct.)
Here is the xml to config this tool with the correct launch link. The correct launch link is in pink.
For this kind of problem, who should I contact in Instructure.com?