Double click the client.wyc file. What does the version say? If it says the latest version, then everything updated fine and the problem is with how you packaged your update. For example, 99% of the time, when customers report this problem what they've done wrong is for a new version of their app they use old files. Or use the same files as the previous version.
To fix your problem, create a new version in wyBuild, set a new higher version number, make sure your new files are inside the corresponding folder on the harddisk, add the files to wyBuild, rebuild the update, re-upload all the update files to your server.