Explain in a lot more detail. Exactly what step of Lightroom is this happening at? Exactly what happens? Can you show us a screen capture?
Please state exactly what version NUMBER of Lightroom you are using (I want the version NUMBER, not words like Lightroom is up-to-date or it is the most recent version). Please state the exact camera model used to take these pictures.
Please give the exact error message you get from Lightroom.