why are am I getting error 050084 when I run "Intersect 3D"

[Elijah]

I am getting this error as shown here each time I tried to intersect these 2 3d features. I am surprised that one of the layers intersected correctly but not others, even when I created them all using same method. The error means the features are not intersected but geographically they are. Does anyone know why?

Also, how can I merge different layers of multipatch together? I am not sure of which tools does that. I ve tried some without success.

[NeilAyres]

ArcGIS version etc.

Are you absolutely sure that the 2 datasets have the same coordinate system? They might overlie in ArcScene, but this could be because of project on-the-fly.

[DanPatterson_Retired]

are both multipatches ? Intersect 3D—Help | ArcGIS for Desktop 

And the available tools for all 3D intersection by geometry type are listed in the same help topic area.  Check out PROs help for other or similar topics