The authentication method 'password' is not available. (97375)

The following error is shown when monitoring a Unix host:

2012-09-13 14:48:25.580 ECHO <HostAgents/5.6.2/UnixAgent/hostname> VERBOSE [Quartz-23505] com.quest.glue.core.remoteconnection.SSHConnectionServiceImpl - Connecting to hostname:22 using login/password authentication
2012-09-13 14:48:25.678 ECHO <HostAgents/5.6.2/UnixAgent/hostname> VERBOSE [Quartz-23505] com.quest.glue.core.remoteconnection.ConnectionPool - Unable to authenticate to host hostname with credential 8c7c30d5-80ec-4ad4-b3ce-801b5671f8cb
com.quest.glue.api.services.CredentialRejectedException: The authentication method 'password' is not available. This server only supports: hostbased, publickey, keyboard-interactive

However, logging into the same host using an SSH client (e.g. Putty) works fine using username and password authentication.