I have copied the compiled widget folder overyou do mean the contents of that folder right? And you copied the contents (i.e. Identify Folder) under your FVs widgets folder right? Are you using ArcGIS Viewer for Flex 3.1?
Manuel,
The fact that you have flexviewers in your path leads me to believe that you are using or have used Application Builder... Is that the case? If so then there is a much easier way for you to add the identify widget to your app.