Problem with HTTParty XML builder and delayed_job

Question

I have a lib Class for a delayed job with httparty.

If I build my XML data in a view data.xml.builder and hand it to my lib Class everything works fine:

--- 
response: 
  status: !str 
    str: OK
    "@attributes": {}

  response: 
    status: !str 
      str: OK
      "@attributes": {}
...

If I build my XML data directly in the lib Class, I get exactly! the same XML-code, but I get errors like:

--- 
response: 
  status: !str 
    str: Error
    "@attributes": {}

  message: !str 
    str: |-
      Bad Request
      Invalid request.
      XMLReader::read(): Unimplemented block at xmlschemas.c:28004
       in Element: text
      XMLReader::read(): An Error Occured while reading
       in Element: text
    "@attributes": {}
...

Any ideas what is causing this?