Don't Allow link generates a 500 Internal Error

Question

I'm developing an application for Facebook using the iframe mode and ASP.NET.

I'm able to use the new OAuth method that combines the allow and the extended permissions. When I click on the Allow everything works as expected, but when I click on the "Don't Allow" I get a 500 internal error. The Request For Permission url is:

http://www.facebook.com/connect/uiserver.php?client_id=389845102120&scope=publish_stream%2Cuser_birthday%2Cemail&redirect_uri=http%3A%2F%2Fapps.facebook.com%2Fplumreward%2FDefault.aspx%3Fpid%3D124733857540930&display=page&next=http%3A%2F%2Fgraph.facebook.com%2Foauth%2Fauthorize_success%3Fclient_id%3D389845102120%26scope%3Dpublish_stream%252Cuser_birthday%252Cemail%26redirect_uri%3Dhttp%253A%252F%252Fapps.facebook.com%252Fplumreward%252FDefault.aspx%253Fpid%253D124733857540930%26type%3Dweb_server&cancel_url=http%3A%2F%2Fgraph.facebook.com%2Foauth%2Fauthorize_cancel%3Fclient_id%3D389845102120%26scope%3Dpublish_stream%252Cuser_birthday%252Cemail%26redirect_uri%3Dhttp%253A%252F%252Fapps.facebook.com%252Fplumreward%252FDefault.aspx%253Fpid%253D124733857540930%26type%3Dweb_server&app_id=389845102120&method=permissions.request&return_session=1&perms=publish_stream%2Cuser_birthday%2Cemail

When I click don't allow it goes to http://www.facebook.com/connect/uiserver.php and then to

http://graph.facebook.com/oauth/authorize_success?client_id=389845102120&scope=publish_stream%2Cuser_birthday%2Cemail&redirect_uri=http%3A%2F%2Fapps.facebook.com%2Fplumreward%2FDefault.aspx%3Fpid%3D124733857540930&type=web_server&perms&selected_profiles=567961887

with a HTTP 500 Internal Server Error.

What am I doing wrong? Am I missing a setting, parameter? Is this a FB bug?