DEBUGGING .net soap client to PHP soap server

We have developed a SOAP based API for an authentication system. The PHP SOAP server will run on liunx/OSX and is working great against a PHP/java client. One of our customers is using .NET and can not use the API with complex types. Any .net calls that return simple types work fine, but as soon as they call a function that returns a complex type like array of strings it errors. The only error they can give us is "no xml document" We need help in debugging the .net client and creating a simple proof that it works. thorough understanding of SOAP,WSDL and .net a must, knowledge of PHP an advantage. Urgent need! Dump of soap return. HTTP/1.1 200 OK Date: Tue, 06 Jan 2009 21:29:10 GMT Server: Apache/1.3.41 (Darwin) DAV/1.0.3 mod_ssl/2.8.31 OpenSSL/0.9.7l mod_perl/1.29 Cache-Control: no-store, no-cache, must-revalidate, post-check=0, pre-check=0 Expires: Thu, 19 Nov 1981 08:52:00 GMT Pragma: no-cache Content-Length: 1692 Connection: close Content-Type: text/xml; charset=utf-8 <?xml version="1.0" encoding="UTF-8"?> <SOAP-ENV:Envelope xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/" xmlns:ns1="urn:xmethods-delayed-quotes" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:SOAP-ENC="http://schemas.xmlsoap.org/soap/encoding/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:ns2="http://xml.apache.org/xml-soap" xmlns:ns3="urn:Authentication/schema" SOAP-ENV:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/"><SOAP-ENV:Body><ns1:getUserSiteGroupsResponse><Result SOAP-ENC:arrayType="xsd:groupInfo[3]" xsi:type="ns3:ArrayOfGroups"><item xsi:type="ns2:Map"><item><key xsi:type="xsd:string">group_id</key><value xsi:type="xsd:string">13</value></item><item><key xsi:type="xsd:string">group_name</key><value xsi:type="xsd:string">qwppe_editor</value></item><item><key xsi:type="xsd:string">pretty_group_name</key><value xsi:type="xsd:string">qwppe_editor</value></item></item><item xsi:type="ns2:Map"><item><key xsi:type="xsd:string">group_id</key><value xsi:type="xsd:string">12</value></item><item><key xsi:type="xsd:string">group_name</key><value xsi:type="xsd:string">BK_Group_Canada</value></item><item><key xsi:type="xsd:string">pretty_group_name</key><value xsi:type="xsd:string">BK_Group_Canada</value></item></item><item xsi:type="ns2:Map"><item><key xsi:type="xsd:string">group_id</key><value xsi:type="xsd:string">5</value></item><item><key xsi:type="xsd:string">group_name</key><value xsi:type="xsd:string">MerkleyDemo</value></item><item><key xsi:type="xsd:string">pretty_group_name</key><value xsi:type="xsd:string">Merkley Demo</value></item></item></Result></ns1:getUserSiteGroupsResponse></SOAP-ENV:Body></SOAP-ENV:Envelope>