Yesterday I was struggling in getting a dynamic partnerlink coupling to work in BPEL PM.
I would not say that I invented the principle of dynamic partnerlinks myself. But lets say that it was not my first time. And what I tried and checked, and double checked, I kept hitting the error:

Error while invoking bean "presentation manager": Cannot find partnerLinkType 2.
PartnerLinkType "{http://www.domain.nl/PROJECT/SUBPROJECT/PUB}PROJECT_PUB" is not found in WSDL at
 "http://localhost:7777/orabpel/default/MyBpelProcess/1.0/_MyBpelProcess.wsdl".
Please make sure the partnerLinkType is defined in the WSDL.

ORABPEL-08016

Cannot find partnerLinkType 2.
PartnerLinkType "{http://www.domain.nl/PROJECT/SUBPROJECT/PUB}PROJECT_PUB" is not found in WSDL at
 "http://localhost:7777/orabpel/default/MyBpelProcess/1.0/_MyBpelProcess.wsdl".
Please make sure the partnerLinkType is defined in the WSDL.

At the end I was so desperate that I thought: "Okay then, lets google the error". Afterwards I could hit myself with the question: "why didn't I do this earlier?". Because the answer was simple and can be found (amongst others) here: Just clear the WSDL cache. Apparently my wsdl updates were deployed but not replacing the occurence in the cache. Ouch.

To my defense I would say that dynamic partnerlinks aren't hard but a mistake is made easy and the dependencies are very sensitive. And also I had to copy an existing solution to adapt it to a new situation. And that is harder than build it yourself. But may be in the future I should consider Google as a closer friend...