[bojan]

Hmmm
Something is not right here.
I opened your file in DSS, and re-saved it as 16-bit tiff, to be able to process it in DPP.
There are some artefacts present to the right of each brighter star (black dots) and the noise is almost as if the stacking did not take place at all.
Maybe you did not follow the DSS procedure correctly?

To stack, you need to just click on "register checked pictures".
Make sure all is checked, and darks and flats are loaded as such (upper part of the left-side menu).
Otherwise I do not know what went wrong here.. but something did, and badly.

And, yes, do not do any curves in DSS... it is painfully slow so it is very hard to control the process