Exception encountered inside [WorkerMicroStationProxy.SetPrintSetSchema]

We're receiving the following message above when opening  a PSET using Print Organizer (MicroStation SS4).

And we're also receiving the following information message:

"There was no endpoint listening at

net.pipe://locahost/21ff1313-4a50-411a-8a6e-4d6a41200c03 that could

accept the message. This is often caused by an incorrect address or

SOAP action. See InnerException, if present, for more details."

Would someone help to explain what this mean?

Thanks in advance for your help.