Zbrush Polypaint weird results


Hello, I am new to zbrush and sculpted one subtool and after that I started to paint it. Everything is ok, but when I went to texture map and I created a “New from Polypaint”, the texture created is half of the one I made. The subtool is a model of a Duck, and the texture result is half of the texture of the ducks body. The subtool is a large one (more then 8 million polys), but when I used decimation master and had it much more smaller the results were not so good. Can you guys help me? Thanks a lot. I attached to the messages the images.