How to "Add Comment" to a Case in zoho CRM

How to "Add Comment" to a Case in zoho CRM

I'm trying to "Add a Comment" to a case in the CRM via a Stateless Form. The code below "should" work but does not.

The caseResp says "Successfully Updated Record". Am I missing something? 
  2.     caseMap = map();
  3.     caseMap.put("Add Comment", "test");
  4.     caseResp = zoho.crm.updateRecord("Cases", "841019000007280001", caseMap);
  5. alert (caseResp) ;