I tried sample codes to open a File GDB Workspace which already exists with the name testGDB.gdb: there is also a sample in EDN, I have ArcGIS 10, Visualstudio 2008. I always get NULL result for the variable "outWorkspace", that is why I cant get any pointer to create a feature class inside the GDB. Is there something I am missing !? any hint !???? I have checked several times, there is no problem with my path ! because the testGDB.gdb is created directly by ArcGIS connString is in my case : C:\Daten\Bearbeitung\testGDB.gdb which goes with the codes.