Could not load file or assembly 'CrystalDecisions.ReportAppS

Hi,
            I am trying to host my report page to server... I got the following error
 "Could not load file or assembly 'CrystalDecisions.ReportAppServer.ClientDoc, Version=13.0.2000.0, Culture=neutral, PublicKeyToken=692fbea5521e1304' or one of its dependencies. The system cannot find the file specified"

Anyone tell me how to solve it...