SOAPAction HTTP header
Problem
The SOAPAction HTTP header is a special HTTP header found in SOAP request messages that contains information about the Web service being called. ASP.NET Web services require this header, and it must contain the namespace and (if applicable) the name of the method being called. If you are using a .NET Framework-based client, this header is automatically generated for you and you do not need to worry about it.
Apache SOAP Web services, however, do not require any information from the SOAPAction header. An Apache Web service will be perfectly happy receiving a message with an empty SOAPAction header (although the header itself must still be included in every SOAP message). In the example earlier in this white paper, we did not provide any SOAPAction in the Apache SOAP client we created; consequently, that client would not work with a .NET Framework-based Web service, even if the location and namespace of the service were the same.
From: http://msdn2.microsoft.com/en-us/library/Aa478995.aspx
只是在找到症结所在之后，才去找到的一点理论依据
具体错误请见前一篇