I made a pair of medieval breeches for James by modifying the P6 swimming costume in a 3D modelling program. 
They imported back into Poser and looked very nice, but when I saved them as a prop, intending to try conforming, they wouldn't reload. Or rather they reloaded without being visible, the circle's there and changes size when the scale parameter is changed.

Each time I re-import them they are visible, so I tried to re-export to UVMapper, which refused with the error  'This Obj has no facet information'

It's strange that it can be seen the first time but  not a second time. Anyone come across this before?

Something happened to the geometry...
By the way, if you were to make a conforming a piece, you'd want to save it as a figure, after you're done with the setup room, no?

Unlike Poser, UVmapper gives nice straightforward error messages.
When it says no facet info, it means that the OBJ has a vertex list
but no facet list.  I'd guess this was lost when you used your
modeller ...  Some modelling apps will let you save only the vertices,
to use as a morph target.  Perhaps you accidentally saved it that way, 
or the modeller decided on its own to save that way.  

If the first import back into Poser looked OK, it could have been because
you had the original OBJ with the same name in a different folder, and 
then you renamed the new one later on?

(When I run into an OBJ that sometimes seems okay and sometimes
not, it's usually because of different versions using the same name
in different folders.)

Went through again, clearing all similar names.
On checking the vertex and facet point, the ,obj file that emerges from the3D modeller has a v list and an f list, presumably why it is visible when first imported into Poser.

When I re export it from Poser as an .obj file to UVMapper it has no f list, which is what UVM reports.  
When I save the visible breeches as a prop to the library, the .pp2 file also has no f list , which presumably is why it doesn't show when I try to bring it back into Poser.

Conclusion; when Poser has to work with this file it fails to copy the facet list.  Why?

1. Is it a Service Release problem? PhilC on the UV forum mentioned a bug fixed by SR 2- my version number is v7.0.2.127, am I up to date?
2. Is it to do with the original export options?-Weld body part seams and Include body part names in polygon groups checked, is something missing?

You seem to have the latest version: "The current Service Release for the English version of Poser 7 is SR2 (as of June 18th, 2007). This updater takes Poser 7 to version 7.0.2.127." to quote e-frontier. There aren't any export options in Poser that would make it omit facet information. It might be handy if there were... One way round this may be to make it into a prop with external geometry, since it seems to be the embedding process that's going wrong. You could keep your existing OBJ file, which works, and edit a "stub" PP2 file to point to it. I'm fairly sure I have an example somewhere, but it will be at home, and I'm not... If you're willing to do a bit of PP2 hacking, look at one of the Poser primitives (which all use external geometry) and you should be able to see what bits to edit to include your file.

Magic.

Opened the no-show breeches pp2 side by side with the primitive Box pp2, changed all the Box references to breeches and then looked for similar parts of the file that had different parameters -all in Offsets? Carefully altered the Box values-all 0 or -0? to the ones in the breeches pp2, noted the path to the Box obj  and altered that to point at the breeches obj. 
Then remembered to copy the breeches obj to that folder (I've forgotten to actually move the target file before, took an hour to realise I was a pillock) . 
Finally saved the Box pp2 under the new name Breeches02, restarted Poser and with bated breath clicked on the tick.  

There it was...well actually there was nothing in view to start with, when I pulled the window out, there 400 feet above the ground plane was the world's biggest pair of trousers, just like a novelty hot air balloon. 
The normals were reversed so I went back to the 3D modeller and reversed them, then saved the breeches obj  back to the right poser folder. A bit of scaling and resaving and I've got my breeches prop.
Now to try turning them into conforming clothing............

EnglishBob, you are the next King of England

:blushing: I'm glad it worked. And for my next trick, a coherent national government based on benevolent dictatorship. Yes, I'd guessed that offsets and scaling would be all over the shop, but once they're corrected you can save the prop back into the library as often as you like, and it will retain its external geometry. The only exception may be after using the grouping tool to edit the mesh; I can't recall what Poser does under those circumstances: create a new external geometry file, or embed it into the PP2. I've seen both on other people's files, and it may be dependent on Poser version. Something to be aware of, anyway.