nlapiLoadRecord - From NS documentation --- This API is supported in all script types
vendor record - From NS documentation ---  Scripting Level = Full,  Scriptable in Client and Server SuiteScripts

Why I am getting this error "SSS_NOT_YET_SUPPORTED" when trying to run the code?

Here is a snip it of code  - On Save Client Script.

   function approvePOSendEmail (type, name)  {      var vendor = nlapiGetFieldValue('entity');      var vRecord = nlapiLoadRecord('vendor', vendor);          var contact = vRecord.getField('phone');      alert(phone);  }