OK, you see how the ant failure shows the actual command line that it's trying to execute? Try running that on just the straight command line, what errors does it give? Check the command line help to make sure what you're passing is valid. Once you've got it gonig correctly on the command line you can fill in the missing bits for the Ant pvcs task.
Also, double check the docs on the ant pvcs task? e.g. Make sure you've filled in the mandatory fields as required..