Arnaud,
the most frequent cause of the problem you are seeing is that the platform build fails, and then you are left with a version of the platform that you successfully built earlier. If that's the case, you would see a message saying that the platform build did not succeed. It's hard to tell why would the build fail, and if that was really a cause, without seeing a platform.
You can try the following. Go to the directory D:\platforms\fmc667 and first open the file Platform.xdc to verify that the memory setup in that file corresponds to the memory from the screenshot you posted. Then, open the command line window in that directory and run:
C:/ti/xdctools_3_23_04_60/xdc
You should see if the build succeeds or if there are some errors. Please let me know how it goes, and you can also just zip up the whole fmc667 directory and post so I can debug further.