I am trying to get Bugzilla with testlink integrated . Added a Isuue Tracker and the green link appears where I can link an existing bug with a failed Test Case . On filing the popup with bug ID I get a blank page http://localhost/testlink/lib/execute/bugAdd.php.
Could you please share with us your Apache error log file when you get that error? You can find it at /installdir/apache2/logs/error.log. Please, don't forget to substitute /installdir/ with your installation directory.