[opencms-dev] how to add user to group with servlet

[Recks Yu]

I use servlet to register user, and want to add the user to groups
"Guests",get error as below.

My code:

  CmsObject cmsObject = OpenCms.initCmsObject("Guest");
  cmsObject.addUserToGroup("99999","Guests");

Get error:

  org.opencms.db.CmsDbIoException: Error adding user "99999" to group "Guests".

many thks!