Unable to merge panels after completing 6 panel mosaic

I didn't see your other post, but 20% overlap should be plenty. I would double check that your camera settings are correct and that you are feeding the right information to the Framing and Mosaic Wizard. The best way to determine your actual image scale is to open one of your raw images and plate solve it within SGP, then make sure the results match what you put in your equipment profile for the camera.
Just a thought...