Well, I'v just done some more small tests and it seems it is related to the (changing of) render dimensions.

The scene was setup with a render dimension of 500x800, but I used the override resolution option (for 1200x1920 dimension) and it failed. I saved/reloaded the scene and changed the render-resoultion in Poser, converted again, and failed again...

Changed the resolution in poser to 600x960, converted again, and -- no problems ---

L3 is indeed Laura, and yes, I used the Forest Mysteria 2 set (and the infinity cove 2 set)

Further testing from me will have to wait a little... different time-zone, it's about 3.00 AM here, time for me to hit the sack... but I will try-out your suggestions....and post the result....

And thank you both for your quick reactions!