Codecs must be installed automatically during the software installation. Make sure that you have the latest version of the Viewer and the Host (Server) installed on the local and remote PCs respectively.
If you still get the error, please report here and we'll see further what the problem can be.
many thanks for your help
i have installed both client and server this morning and during install was asked to check for updates which it said there was none ..also i just check this manually from the help menu and again was all uptodate
i installed viewer on another computer to rule out and problems with the initial computer viewing it and i get the same warning
any help would be appreciated