Using SOAP, I'm trying to log on to the Partner API. I can log in, change the service URL and I can create a SOAP Header with the Session ID and token.
I'm logging in with the username set to the account holder email address. This user is a System Administrator. The password is the salesforce password followed by an API Key.
However, when I try and call "DescribeGlobalResult" or "getServerTimestamp" or "getUserInfo" I get the error "SessionID Invalid at this location". I'm assuming that there are some API Security rights I need to set, but I can't find these.
What causes this error? How do I fix it?