Is it an authentication error that you are getting like the following?:
"HTTP request sent, awaiting response... 401 Authorization Required Authorization failed"
Your command syntax works fine for my on Fedora 13, GNU Wget 1.12. Perhaps its a character in the password that is causing problems if its not escaped properly, i.e. if it contains a ! or "... it may need to be escaped with a backslash before it.
If your version off wget supports it, you can also try the following:
wget --user=admin --ask-password 10.0.0.1/filename
then type the password when prompted, it will at least confirm that the wget/username/password combination is actually working.