Exporting to 3D File (Product View 9.1)

Hello .. hopefully someone can help me on this, Im using Productview 9.1 and I need to export a sub set of a large model to a 3D file, either IGS or STEP. 

So I have isolated the items I want to export but when I do a "save current view as ... save 3D file" I get this error: "no analytic data to write to 3d file" ...

I am not overly familiar with the software and cant seem to find the user manual anywhere, there doesnt seem to be a help option within the software ...

Any help gratefully received!