First Update your camera raw plugin from Help > Update .
If it is already updated , use Adobe DNG Converter, a free utility that converts files from more than 350 cameras to DNG, enables you to easily convert camera-specific raw files to a more universal DNG raw file.
What camera are you using?
Here is the list of cameras supported by different ACR versions:
Please look into this list and see if your camera is supported by the ACR version you are using.
If it's not, then download and install the free Adobe DNG converter to convert your CR2 files to the Adobe universal Raw format and the files will open in all versions of PSE (keep your original CR2’s as backup) or for use in Canon DPP bundled with your camera.
Windows download click here DNG Converter 7.2
Mac download click here DNG Converter 7.2
You can convert a whole folder of CR2 images in one click. See this quick video tutorial:
It may not be a Canon. Don't assume CR2 files.
Your camera only gets full support in version 7.3 which is out of beta testing and now available as a release candidate. You may want to wait for the final version of camera raw 7.3 which will be available shortly. Alternatively download the release candidate now but make a note to update when the final version is released.
Adobe Labs Downloads click here DNG Converter 7.3 RC