depending on the errormessage you get, it may be MySQL itself preventing your to sign in. Best would be to sign in locally and check the mysql.user table:
Access to MySQL is regulated on a host/user combination. If the host value is '%', access from outside is allowed. Typically, root access is limited to "localhost", you have to consider yourself what you want to do: open up root access or create a dedicated remote user.
Level 197 Nanomage NT from Rimor speaking... err, wait: Wrong Forum!