3D Features in Oracle Locator

This is probably something I am just doing wrong, but I am having trouble loading my 3D features (buildings) into our Oracle Server (11g).

I have created me GSA project and created a couple of features, now I want to load these into Oracle.  I used the 'dgn2sdo' utility to create the Oracle scripts to upload the data, but this seems to have failed.

In my DGN2SDO logfile I found these lines:

Commencing translation
ERROR: Error encountered while translating instances = (Exception of type 'System.NotSupportedException' was thrown.).
System.NotSupportedException: Exception of type 'System.NotSupportedException' was thrown.
   at Bentley.EngineeringContent.Storage.Xfm.ECXfmSupport.ManufactureInstanceToStore(opaquePointer* feature, Char* pFacilityUuid, IOgcSpatialReference targetSpatialReference, ECObjectToXfmWorkingStorage workingStorage, Boolean populateOnlySimpleProperties)
   at Bentley.EngineeringContent.Storage.Xfm.ECXfmScanDgnInstanceCursor.Read()
   at Bentley.Geospatial.Dgn2Sdo.Dgn2SdoTranslator.Translate(IECInstanceCursor instanceCursor)
ERROR: Error encountered while translating instances = (An unsupported Microstation element type of 94 has been encountered, and cannot be converted to an OGC geometry type.).
System.ApplicationException: An unsupported Microstation element type of 94 has been encountered, and cannot be converted to an OGC geometry type.
   at Bentley.EngineeringContent.Storage.Xfm.ECXfmSupport.ManufactureInstanceToStore(opaquePointer* feature, Char* pFacilityUuid, IOgcSpatialReference targetSpatialReference, ECObjectToXfmWorkingStorage workingStorage, Boolean populateOnlySimpleProperties)
   at Bentley.EngineeringContent.Storage.Xfm.ECXfmScanDgnInstanceCursor.Read()
   at Bentley.Geospatial.Dgn2Sdo.Dgn2SdoTranslator.Translate(IECInstanceCursor instanceCursor)
Total instances read = 2
Total instances written = 2
Translation completed

 And when I check my DAT file the third dimension is missing from each surface of my building.

I am using Bentley Map Enterprise and Oracle 11g (not Oracle Spatial).

So what is the correct process for creating and 3D features in Oracle?

Regards Ian