To reproduce the bug:
0. Update your Moodle to the latest 1.8.x CVS version, then turn on debugging to the ALL level
1. create a GIFT questions text file to be imported
2. test it against the quiz module import, and make sure the GIFT file works at least here
3. now create a Lesson Module, and select Import question from file
4. select GIFT as the import format
5. select and upload the previously created GIFT formatted file
6. Moodle returns: Fatal error: Call to undefined method qformat_gift::try_importing_using_qtypes() in /yourmoodlepathl/moodle/question/format/gift/format.php on line 228