I cannot figure out why `netdom join` is not working

I cannot get netdom join working on Windows Server 2008 R2.

netdom join bananas /domain:fruitland.local /userd:fruitland\Administrator /passwordd:*

Logon failure: unknown user name or bad password.

The command failed to complete successfully.

The local admin account I am using is has the same name and password as the domain admin account. I've double checked DNS and passwords. I can ping the DC. The DC accepted netdom join from a Windows Server 2003 R2 machine earlier. I've made sure that the older version of netdom for pre-Vista is not in the path.

However, when I go through the GUI System Properties > Computer Name and enter the same domain, username and password, it works fine. The only difference I can see is that the user account details dialogue box is already set to use a domain, with the top level domain at the end.

So I tried:

netdom join bananas /domain:fruitland.local /userd:fruitland.local\Administrator /passwordd:*

...but that did not work either. I get the same error.

I must be getting something wrong, as the GUI method works fine.