Can't login to Last.FM for audioscrobbler

Entered my userid/password into the Last.FM Audioscrobbler settings and got error message for an invalid username.

[16-10-22 10:26:16.7468] Slim::Plugin::AudioScrobbler::Plugin::_handshakeOK (351) Invalid Last.fm username or password.

I can use the same userid/password on the last.fm website with no problems.

I'm a last.fm free user - ie. no subscription. Am I missing something here?