'Content type was not the expected type' error

I'm getting the following error when attempting to submit a web service call using the Web Services protocal:
HTTP/1.1 415 Cannot process the message because the content type 'text/xml; charset=utf-8' was not the expected type 'application/soap+xml; charset=utf-8'.)

I read elsewhere that this could be due to a  SOAP version conflict.
SOAP v1.1 uses text/xml while SOAP v1.2 uses application/soap+xml.
Is this correct?
Is that the problem?

I am using Loadrunner 11.52. Does it support SOAP v1.2?

What is the solution?