Problem with GRANT ... 'user'@'%'

[Miguel Cardenas]

Hello list

I have a problem adding a user with host '%' ...

*** If I add a user with host '%' when trying to connect get this error:
ERROR 1045 (28000): Access denied for user 'myuser'@'localhost' (using 
password: YES)

*** If I add the same user with localhost it connects and works fine...

My specific doubt is:

1) do I need to add a same user with both '%' and 'localhost' to connect 
locally and from another location???, or...

2) for some reason a host '%' is not working or need to do something so it 
allows connections from any host?

Thanks for your help