Cannot copy InfoPath form from K2 to SharePoint: The request failed with HTTP status 401: Unauthorized

Hi

I've recently migrated a K2 process from our dev environment into our test environment. Although the code below has not changed between each version it is now generating an error in K2:

 if(spsList.UploadDocumentFromUrl(strWorkSpaceName, FileURL, oByte, true, ref errMess))
 {
    Console.WriteLine("Trying to upload document from url...");
    //do more stuff
 }

The error that is thrown is: The request failed with HTTP status 401: Unauthorized. What is the cause of this error? Why has it begun to occur even though this code has not changed?

Best Regards
Tim