add domain using mail api

add domain using mail api

Hi, I hope you can help me
each time I can to use the api for call to add a domain to the user.
I keep getting {"data":{"errorCode":"JSON_PARSE_ERROR"},"status":{"code":404,"description":"Invalid Input"}}

not sure what is the trouble
the body of it is array('domainName' => $domain) 

if you need anymore info feel free to ask