Be careful!
OMG! I wasted *several* mandays of my worktime AND also wasted many days of my free lifetime (when I should have been with my family!) because of this ellusive detail - which turned out to be an error in WSDL in the end!!
So, by all GODS, by all means beware of it, please.
Reminder:
relative reference "a" relative to a base "b/c?d" resolves to "b/a".