I called the GetIndividualCollection method and searched by last name. For most queries it seems to work fine, but it failed when I did one search. After inspecting the output, the XML you're sending back is invalid:
<middleName>
</middleName>
<goesByName>
</goesByName>
n>
<prefix>
</prefix>
Notice the "n>" partial tag. Other records respond correctly. I've only seen this on one record so far - I'd be happy to help you track down the offending record.
Thanks,
Eric