The debug thing didn't seem to make any difference, but I turned on on_debug function and that gave me loads of stuff, i've removed passwords from it, but here's the output otherwise.

POST https://adwords.google.com/api/adwords/v2/ReportService HTTP/1.1 
+Accept: text/xml Accept: multipart/* Content-Length: 1349 Content-Typ
+e: text/xml; charset=utf-8 SOAPAction: "" usernamepassword Company --
+ Report Service DemomLJY5JKVDelqtK74RxOt5wSummary2005-08-11T00:00:005
+214135testAveragePositionClicksCpcKeywordAdGroupId2005-08-04T00:00:00
+ HTTP/1.1 500 Internal Server Error Cache-Control: private Connection
+: Close Date: Thu, 11 Aug 2005 11:33:39 GMT Server: GFE/1.3 Content-T
+ype: text/xml; charset=utf-8 Client-Date: Thu, 11 Aug 2005 11:33:37 G
+MT Client-Peer: 216.239.59.112:443 Client-Response-Num: 1 Client-SSL-
+Cert-Issuer: /C=ZA/ST=Western Cape/L=Cape Town/O=Thawte Consulting cc
+/OU=Certification Services Division/CN=Thawte Premium Server CA/email
+Address=premium-server@thawte.com Client-SSL-Cert-Subject: /C=US/ST=C
+alifornia/L=Mountain View/O=Google Inc/CN=adwords.google.com Client-S
+SL-Cipher: AES256-SHA Client-SSL-Warning: Peer certificate not verifi
+ed Client-Transfer-Encoding: chunked soapenv:Server.userExceptionorg.
+xml.sax.SAXException: No deserializer defined for array type {http://
+www.w3.org/1999/XMLSchema}ur-typeorg.xml.sax.SAXException: No deseria
+lizer defined for array type {http://www.w3.org/1999/XMLSchema}ur-typ
+e at org.apache.axis.encoding.ser.ArrayDeserializer.onStartElement(Ar
+rayDeserializer.java:267) at org.apache.axis.encoding.DeserializerImp
+l.startElement(DeserializerImpl.java:399) at org.apache.axis.encoding
+.DeserializationContext.startElement(DeserializationContext.java:1038
+) at org.apache.axis.message.SAX2EventRecorder.replay(SAX2EventRecord
+er.java:159) at org.apache.axis.message.MessageElement.publishToHandl
+er(MessageElement.java:1138) at org.apache.axis.message.RPCElement.de
+serialize(RPCElement.java:199) at org.apache.axis.message.RPCElement.
+getParams(RPCElement.java:342) at org.apache.axis.providers.java.RPCP
+rovider.processMessage(RPCProvider.java:146) at org.apache.axis.provi
+ders.java.JavaProvider.invoke(JavaProvider.java:319) at org.apache.ax
+is.strategies.InvocationStrategy.visit(InvocationStrategy.java:32) at
+ org.apache.axis.SimpleChain.doVisiting(SimpleChain.java:118) at org.
+apache.axis.SimpleChain.invoke(SimpleChain.java:83) at org.apache.axi
+s.handlers.soap.SOAPService.invoke(SOAPService.java:450) at org.apach
+e.axis.server.AxisServer.invoke(AxisServer.java:285) at org.apache.ax
+is.transport.http.AxisServlet.doPost(AxisServlet.java:637) at javax.s
+ervlet.http.HttpServlet.service(HttpServlet.java:709) at org.apache.a
+xis.transport.http.AxisServletBase.service(AxisServletBase.java:301) 
+at javax.servlet.http.HttpServlet.service(HttpServlet.java:802) at co
+m.google.gse.HttpConnection.runServlet(HttpConnection.java:393) at co
+m.google.gse.HttpConnection.run(HttpConnection.java:334) at com.googl
+e.gse.DispatchQueue$WorkerThread.run(DispatchQueue.java:219)
[download]

Thanks,
Tom