I tryed your CAPX and it works with Q
As far as I can remember from college, keyboards are physicly divided into sectors. Each sector is scanned seperatly and alow only so many keys pressed at the same time to be recognized.
If you now have more keys you want to be read, then the resolution of the sector allows, you have to move one key to another sector....
....this could have changed, but 20 years or so ago, this was how it worked!