Add attachment to a list using rest

Hi everyone

I have used this:

NWF$.ajax(

   { url: _spPageContextInfo.webAbsoluteUrl + "/_api/web/lists/getbytitle('test3')/items(" +    IDfrm + ")/AttachmentFiles/ add(FileName='" + fileName +    "',overwrite=false)?   $expand=ListItemAllFields",

  method: 'POST',

...

In oreder to add file from input,

What could be the problem?