Today’s error of joy in my performance testing Jmeter life was when I was using the WebService(SOAP) request sampler. I had pasted some XML that I know works as I was using soapUI initially to test the webservice. I was surprised to find that I got an “SOAP-ENV:VersionMismatch: Envelope element must be associated with the ‘http://schemas.xmlsoap.org/soap/envelope/’” error.
A bit of googling suggested that you should use the Jmeter SOAP/XML-RPC sampler instead. This does indeed work but the post didn’t explain why. A bit of further research suggests that the problem is that the WebService(SOAP) sampler supports the SOAP 1.1 standard and should the XML you are using not confirms to that standard then an error will occur. While the Jmeter SOAP/XML-RPC sampler is a bit more of a blunt instruments and just send the XML payload without checking