mounting SMB shares

Hey everyon, I have a brand new MacBook Pro that needs to be run in an existing AD encironment. It's a 2003 AD. I can successfully bind the computer to the AD, so credentials are not a problem. I cannot, no matter how hard I try, get it to mount the SMB share on the 2003 server. I have everything correct (or so I thought). smb://acoredc/shared user_name password workgroup I keep getting an unknown username or password error message Any thoughts? Tanks, Andrew