.NET event handling Server / Client callback error when opening page 41 / 42

Hi.
I really hope I formed the head of my question to make some sense.

I am very new to C/AL . The only things I know is from some specific googleing.

The problem is:

I have my own .NET assembly that selfhosts a simple WCF service, meaning that I can run an URL in a webbrowser e.g
http://localhost:8888/MessageService/ins766/SendMessageAndKey?Message=1002&Key=2

My service listenes for this URI and triggers an event.

This works ok as long as I only try to show a message box. But trying to open an order or quote , I get an error:
'Microsoft Dynamics NAV Application Server attempted to issue a client callback to run page 42 Sales Order. Client callbacks are not supported on Microsoft Dynamics NAV Application Server.'

The C/AL code looks like this:

Variables:

Documentation()

OnRun()

NavEventHandler := NavEventHandler.NavHandler();
IF NavEventHandler.HostOpen THEN BEGIN
MESSAGE('Host is running with URI: %1', NavEventHandler.BaseAddress.AbsoluteUri);
  END 
  ELSE
MESSAGE('Host is not running');

//Test fire from withing the class allows the page to be open:
NavEventHandler.FireInTheHole();

NavEventHandler::ChangedEvent(recordId : Text;recordType : Integer)

MESSAGE('Lookin for: %1 . Type: %2',recordId,recordType);
saleRec."Document Type" := saleRec."Document Type"::Quote;
saleRec."No." := recordId;
saleRec.SETCURRENTKEY(saleRec."No.");
 IF saleRec.FIND('=') THEN BEGIN
MESSAGE('I Found a/an : %1', saleRec."Document Type");
  //orderPage.SETRECORD(saleRec);
  //orderPage.RUN();
  END
 ELSE
MESSAGE('now i Find a/an : %1', saleRec."Document Type");

NavEventHandler::LogEntried(logEntry : Text)

If I run the event from within the class using FireInTheHole method. It works just fine, and it can open a page.

Any thoughts are greatly appreciated

Best regards
Søren