How to appcfg rollback my project?

I am using Google App Engine to upload my python project However once I try to upload my project I receive this error: ``` 2013-07-24 20:21:06 Running command: "['C:\\Python26\\python.exe', '-u', 'C:\\Program Files\\Google\\google_appengine\\appcfg.py', '--no_cookies', u'--email=thomasston54321@gmail.com', '--passin', 'update', 'C:\\Users\\Thomas Stone\\Documents\\proxy-server']" 08:21 PM Host: appengine.google.com 08:21 PM Application: mathsonlinegames; version: secureable 08:21 PM Starting update of app: mathsonlinegames, version: secureable 08:21 PM Getting current resource limits. Password for thomasston54321@gmail.com: 08:21 PM Scanning files on local disk. Error 409: --- begin server output --- Another transaction by user Thomasston54321 is already in progress for app: s~mathsonlinegames, version: secureable. That user can undo the transaction with "appcfg rollback". --- end server output --- 2013-07-24 20:21:16 (Process exited with code 1) You can close this window now. ``` Because of this I have tried this in CMD: ``` cd C:\Program Files\Google\google_appengine appcfg.py rollback C:\Users\Thomas Stone\Documents\proxy-server ``` But then I receive this error in CMD ``` Usage: appcfg.py [options] rollback <directory> | <file> appcfg.py: error: Expected a single <directory> or <file> argument. ```