A lot of older Canon cameras have problems with SDXC cards due to the lack of exFAT support. This isn’t a problem in your case since your camera is SDHC compatible, so you can still find memory cards without too much trouble.
HOWEVER, this will gradually become an issue as SDXC cards become more common as the cameras that support them replace the old ones that don’t. Do not assume something will work unofficially with Canon; it probably won’t.
The first thing I’d check is what your camera supports vs the card you purchased. It’s possible you bought an SDXC card and you’re now finding out your camera outright lacks the ability to even try and use these cards. As a general rule with Canon, they do not leave unofficially supported features in their camera so the odds of support being found on many of the older cameras is very unlikely; anything not listed is done at your own risk. You will need to find a camera with proper SDXC support to use this card if you do not want to return it or put it in the package and hold onto it.
Follow this for buying a card
- SD cards only go up to 8GB. Smaller cards were removed from production years ago. These are nearly impossible to find.
- SDHC runs from 8-32GB. These are readily available.
- SDXC is 64GB+. These do not work in most old cameras because exFAT is mandatory.