Take a look at the Document log. It will be in the same directory as the qvw and will be named "mydocument,qvw.log". If there is no log file, open the document, Settings, Document Properties, General, check "Generate Logfile". Then rerun and look at the logfile to determine the specific cause of the error.
Please help me out here. Thought I have checked "Generate Logfile" it is not generating the logfile. My problem QVW is not getting refreshed and I am not able to find out what could be the issue as it is not generating the logfile :-(.