If you upgraded your flash player already to the newest version but the tool somehow is limited to an older version of Flash, use the flash uninstaller and downlaod an outdated version of flash (like here)
Follow these steps and it should work:
In extention manager go up to tools and click convert MXP to ZXP
(For this step you need 7-ZIP it is neccessery) Right click on ZXP and click 7-ZIP,
In 7-ZIP right click the MXI and click edit, change the maxvision from 11.5 to 12,and save it
Go back to Extention Manager and install the ZXP as usual.
When installed go into flash (if already opened close it and open it again) go up to WINDOWS-OTHER PANELS (NOT EXTENTIONS) AND YOU'LL FIND KEYFRAME CADDY)