If you mean the ampersand is converting to "amp;" instead of "&", that's a problem. If you mean that it's not appearing as "&", that's by design

From the XML specification at http://www.w3.org/TR/xml/#syntax:

The ampersand character (&) and the left angle bracket (<) MUST NOT appear in their literal form, except when used as markup delimiters, or within a comment, a processing instruction, or a CDATA section. If they are needed elsewhere, they MUST be escaped using either numeric character references or the strings " & " and " < " respectively. The right angle bracket (>) may be represented using the string " > ", and MUST, for compatibility, be escaped using either " > " or a character reference when it appears in the string " ]]> " in content, when that string is not marking the end of a CDATA section.