I tried the examples I gave you. They work (for me). Just changed the real computername, accountname and password with dummies. The only difference I see is you put the computername and the password in a variable and are using the local admin account. In your case, I would avoid using vars in strings and write something like:
Code:
Shell '%COMSPEC% /c net Use \\' + $Computer + ' ' + $Password + ' /user:ComputerName\AdminAccount > NUL'
