Twitter does not send me back or (anywhere) after authentication

[SuperSambo]

hi,
I'am trying to set up yourtwapperkeeper but I can't finish the authentication because Twitter does not send me back after clicking sign in. the apache error log says

PHP Notice:  Undefined index: access_token in /home/supersambo/www/twapperkeeper/index.php on line 106

any idea what Iam doing wrong.

thanks a lot!