In the target settings window, just uncheck "Rotate Camera". This means it will no longer check the camera rotation before the sequence starts.
When you used the image from Astrobin, SGP imported the rotation angle of that image, but your camera will inevitably be at a different angle. So SGP is trying to move your camera to the same angle as the Astrobin image. Be aware that your mosaic panels may be off since the angle doesn't match the reference image.
When it comes to mosaics I can't imagine trying to do a mosaic without the framing and mosaic wizard. It makes mosaics so easy and you can set the angle to whatever you need and you see exactly what field of view is.
