Good solves, on target but failure message

I am still having a problem with the following: the scope is ready to centre on a region that the scope is already pointing at (frame and focus good) and then sequence is run:
plate solver gives a quick solution and decides on a small correction. It moves the scope and re-images and does another plate-solve.
At this stage something goes wrong and an error message comes up even though its right on target, telling me 'something terrible has happened and it is going to try and recover …

Obviously I must have a setting wrong somewhere.

Lawrence (122.0 KB)