QtXml can't properly resolve xml with char "&" in it

Code:

<program>
 <id>1306917122529</id>
 <starttime></starttime>
 <endtime></endtime>
 <layout><slide fileURL="E:/123&.jpg"/></layout>
 <title><![CDATA[1080*1920-ff]]></title>
</program>

Code:

dom = QDomDocument()
        dom.setContent(xml)
        root=dom.documentElement()
        p_nodeList = dom.childNodes()
        i=0
        while i<p_nodeList.count():
            nodeList=p_nodeList.at(i).childNodes()
            print nodeList.count()
            i=i+1

i used above code to print the counts of the children of a program node, For xml with "&" in it ,output is 4, but if i delete "&", output is 5,so why this happen?

sry for my english and thx in advance