Export .DWG AutoCad, Audit error

I am trying to export a model as a .dwg but keep getting this error message. Anyone can help? Thanks

My audit file:
A c D b B l o c k R e f e r e n c e ( 5 D B 8 D ) M a t e r i a l A c D b B l o c k R e f e r e n c e ( 5 D B 9 0 ) M a t e r i a l A c D b B l o c k R e f e r e n c e ( 5 D B 9 3 ) M a t e r i a l A c D b B l o c k R e f e r e n c e ( 5 D B 9 9 ) M a t e r i a l A c D b B l o c k R e f e r e n c e ( 5 D B A 2 ) M a t e r i a l A c D b B l o c k R e f e r e n c e ( 5 D B A 5 ) M a t e r i a l A c D b S e q u e n c e E n d ( 5 D B 8 F ) M a t e r i a l I A c D b S e q u e n c e E n d ( 5 D B 9 2 ) M a t e r i a l I A c D b S e q u e n c e E n d ( 5 D B 9 5 ) M a t e r i a l I A c D b S e q u e n c e E n d ( 5 D B 9 B ) M a t e r i a l I A c D b S e q u e n c e E n d ( 5 D B A 4 ) M a t e r i a l I A c D b S e q u e n c e E n d ( 5 D B A 7 ) M a t e r i a l I

Is the creation of the DWG file totally skipped? If not, what is in the resulting file?
2D or 3D DWG? What if you uncheck Materials from the Export Options? Can you post the model?