That's it....so it would appear that one of these two calls are failing in your environments. You might just want to create a test program and try this yourself to see if you can determine if an exception is being thrown.
Also, this should have abolsutely nothing to do with the latest build as this portion of the import wizard has not changed in a very long time and the import is working for us as well as a number of other users on this same build (even using the DBC provided by Edhy).
Let me know if you have any insight or exceptions thrown with the above code and then we may be able to figure out an all around solution.