Can you send me the screenshot of your Button settings what you have given in Report settings. And is your machine running Nprinting service. ?? Just a thought.
Please let me know or send me a screen shot of report settings.
Strange, everything looks ok to me. However, i can see some one posted something similar to the error you have sent. Please follow this link if that helps you. I am sorry of not being much help at this point. I will try look into other options at my end. However, please follow this link and check at your end. If possible can you post your sample .qvw file, will check at my end.
Just a quick question, if you open the task manager in the machine where your Nprinting service is running, are there two QV.exe files running?? Can you check?