diff --git a/docs/index.rst b/docs/index.rst
index e1da1e2..fcd48c3 100644
--- a/docs/index.rst
+++ b/docs/index.rst
@@ -121,6 +121,11 @@ redirected back to. For example::
         return twitter.authorize(callback=url_for('oauth_authorized',
             next=request.args.get('next') or request.referrer or None))
 
+For the callback to work, you must set a placeholder "Callback URL" in your
+app's "Settings" tab at https://dev.twitter.com. The URL configured in this
+settings page isn't actually used, but not setting it will prevent the
+authorize() call mentioned above from working.
+
 If the application redirects back, the remote application will have passed all
 relevant information to the `oauth_authorized` function: a special
 response object with all the data, or ``None`` if the user denied the
diff --git a/flask_oauth.py b/flask_oauth.py
index b21105a..8193860 100644
--- a/flask_oauth.py
+++ b/flask_oauth.py
@@ -295,8 +295,10 @@ def generate_request_token(self, callback=None):
             self.expand_url(self.request_token_url), callback,
                 self.request_token_params)
         if not self.status_okay(resp):
-            raise OAuthException('Failed to generate request token',
-                                 type='token_generation_failed')
+            msg = "Failed to generate request token." \
+                  + " Response code: '%s', response content: '%s'" \
+                      % (resp['status'], content)
+            raise OAuthException(msg, type='token_generation_failed')
         data = parse_response(resp, content)
         if data is None:
             raise OAuthException('Invalid token response from ' + self.name,