Error while running Google App Engine : unable to open database file

I have tried adding "--clear_datastore" flag but it still doesn't work. Does it have something to do with my OS? My OS is Window开发者_如何学编程s 7 and I'm using Python 2.5 .

App Engine DSK release: "1.5.1"

Error Reports:

2011-06-22 21:16:55 Running command: "['C:\\Python25\\pythonw.exe', 'C:\\Program Files\\Google\\google_appengine\\dev_appserver.py', '--admin_console_server=', '--port=8080', 'D:\\ChemicalWiki\\ChemData']"
INFO     2011-06-22 13:17:21,029 rdbms_sqlite.py:58] Connecting to SQLite database '' with file 'c:\\users\\\<username>\\appdata\\local\\temp\\dev_appserver.rdbms'
ERROR    2011-06-22 13:17:21,036 dev_appserver_main.py:623] <class 'sqlite3.OperationalError'>: unable to open database file
2011-06-22 21:17:21 (Process exited with code 1)

It may be because you have unicode characters in your username or maybe it just can't get your username for some reason (c:\users\username\appdata\local\temp\dev_appserver.rdbms). Try running app engine launcher with the admin flag or if it had been working previously, just delete the database file.