Look closely at your XML. If I write them in one line it's actually
<RECEIPT type="merchant" format="xml">\n\t\t\t<![CDATA[...]]>\n\t\t\t</RECEIPT>
So the tree will actually look something like:
RECEIPT
/ | \
\n\t\t\t CDATA \n\t\t\t
So you got three children. As you are only getting the first child, you're only getting \n\t\t\t
.
Loop through all the children and concat their data and you should have everything.