Sharepoint Task Assigned To field, not set

I am using Blackpearl sp1

I am trying to evaluate K2 blackpearl, and have created a simple workflow which is integrated with a Sharepoint document library.
The workflow is started manually, and basically gets approval of a document, from 3 people in parallel, and then a manager if all 3 of the initial people approve the document.

I find that when the task is sent to the recipients, they recieve an email, and yet when I look at the task list in Sharpoint, the task is not assigned to anyone - the Assigned To field is blank.

Can anyone tell me what is going wrong here? Is there something I need to do?

To ensure that I haven't missed something, here are the steps that I have taken in creating each task:
* Create a new Project
* Add the Sharepoint Workflow Integration process wizard to the process and configure. All tests work to the servers.
* Add a Sharepoint Workflow Integration Client to the workflow, and configure it, setting the desination user to a user that is selected by browsing using the Context Browser, Selecting the User Browser Tab, expanding Users, expanding K2, and selecting my domain user account (I have also set this to be the process originator, and it still doesn't assign the task properly)
* Project deploys correctly, and I can start the workflow. I get the emails, however the task is not assigned to anyone in Sharepoint.

If I look at the workflow status for the document, it displays the following:
"A new task has been created for K2 Users", and the task is created, but the assigned to field is not set on the task

I look forward to any assistance that anyone can offer here.

Thanks in advance