Sorry – the reply was cut directly from the Users Guide. Please refer to the documentation to see the image referred to.
Obtaining the list of users is not related to a successfull login, it simply means the API used by the solution is able to ‘see’ the user list.
Logging into a users account requires a) the Trusted Application to be created and synchronized throught your GroupWise system, and b) Post Office properties to have been correctly defined for each Post office. Problems like the one you describe are generally caused by the later.