Windows Service User Account

I am trying to install a service on my machine to run under the admin account. Everything I have found on the web just tells you how it should work, but I am having problems finding anyone having errors. What I have in my ServiceProcessInstall setup is this:

.account = ...User
.username = "Domain/Admin"
.password = "AdminPassword"

The error I am getting is a System.ComponentModel.Win32Exception that says 'No mapping between account names and security IDs was done'.

I'm thinking that it is pretty simple, but I cannot find anything. Thanks,

To be perfectly honest I don't know what your problem could be, but I looked up your error and found this: http://www.dotnet247.com/247reference/msgs/46/233303.aspx.
I don't know if that's helpful, but for what it's worth it's there.