Hi, I'd like to know if CHDK works on every Ixus 220 HS.
Unfortunately, there is really no way to tell. Canon does not publish a list so the only way we know about a firmware version is when somebody does the work to discover the firmware version of their camera and posts that information here or on the appropriate wiki page.
Are there problems some problems depending on the firmware?
There are occasionally bugs that creep in between CHDK versions for different firmware releases but IMHO its not very common based on what I've seen here on the forum. Once CHDK becomes available for a camera, the port to other firmware versions has become pretty easy to do correctly.
Based on your question, I'm guessing that you might want to read through this forum thread ->
http://chdk.setepontos.com/index.php?topic=7091And as always, this is an important first read so that you understand a bit about the process used around here :
link> CHDK FAQ : My camera isn't ported yet
