Connect Edition saving 3d models from dgn to dwg format

Hi,

When saving (using save as) my 3d models from Connect Edition dgn format to dwg I am finding that the models become just a series of 2d lines when opened up in ACAD and lose all intelligence.

I also note that the files increase in size quite considerably.

Are there some settings that I need to check or uncheck when using the 'Save As ' command.

Please advise,

Ged Etherington