Generally that should work. Maybe your AC21 file is corrupted?
Open an empty template in AC21, save it, and try to open it in AC22 to see if it works. If it does, then it must be because of the other project file.
Try opening the AC21 file in AC21 with Open&Repair (even if it says "the project was healthy", it can fix some things sometimes), and see if it works afterwards.
If Open&Repair doesn't help, please send in the ARCHICAD crash report, save the Bug ID you get, and send me the AC21 project and the Bug ID, so that I can take a look.
Daniel Alexander Kovacs
Professional Services Consultant
For Troubleshooting and useful Tips & Tricks visit