What is the version of Data ONTAP you're using?
These commands (tapeMc category) are supported only on 8.3.0 or above. Any lower version is likely to throw the 'api not found' error.
The error may also be thrown if you're logged in with insufficient privileges. If you're using 8.3.0 or above, please try logging in as cluster administrator and then running the cmdlet.
Hope this helps!