Project Server 2010 Web Services Returns “Unhandled Communication Fault occurred”

I'm trying to use SOAP web services with Project Server 2010 to get project information using Python. However, I'm always getting the fault “Unhandled Communication Fault occurred” with detail “Sequence contains no elements”. Does anyone have any suggestions on how to debug this, and what I should be looking at?

Example SOAP message to Project.asmx:

<?xml version="1.0" encoding="UTF-8"?>
<SOAP-ENV:Envelope xmlns:ns0="http://schemas.microsoft.com/office/project/server/webservices/Project/" xmlns:ns1="http://schemas.xmlsoap.org/soap/envelope/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/">
   <SOAP-ENV:Header/>
   <ns1:Body>
      <ns0:ReadProject>
         <ns0:projectUid>f63f7ed4-d5b1-4c80-a5fa-ccb587d466c2</ns0:projectUid>
         <ns0:dataStore/>
      </ns0:ReadProject>
   </ns1:Body>
</SOAP-ENV:Envelope>

Response back from Project Server:

<?xml version="1.0" encoding="UTF-8"?><SOAP-ENV:Envelope xmlns:ns0="http://schemas.microsoft.com/office/project/server/webservices/Project/" xmlns:ns1="http://schemas.xmlsoap.org/soap/envelope/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/">
<s:Envelope xmlns:s="http://schemas.xmlsoap.org/soap/envelope/">
  <s:Body>
    <s:Fault>
      <faultcode xmlns:a="http://Microsoft.Office.Project.Server">a:ProjectServerFaultCode</faultcode>
      <faultstring>Unhandled Communication Fault occurred</faultstring>
      <detail>
        <string xmlns="http://schemas.microsoft.com/2003/10/Serialization/">Sequence contains no elements</string>
      </detail>
    </s:Fault>
  </s:Body>
</s:Envelope>

The same thing occurs when I call ReadProjectStatus().