Can not find a new user

[YanFeiHu]

Hi Team;

     There is a quesion that strange to say!

     I created three users are 'ZS', 'LS', 'WW'.  And created a site 'testSite'

    Then I try to add these three users into 'testSite', I can use the Search function find 'ZS' and 'LS' but without 'WW'!

    And I can login Share system with user 'WW',  could you please tell me what's the question with user 'WW'?

   Thanks!