Problem with dark sky

Hello ZWO team and hello all.

I need support and i hope to get some answer here...

I have the camera ASI1600 mm cool PRO and i have one problems now that i can't solve.

In all my picture the sky have this big noise and i can't remove.

https://postimg.cc/image/5zugjdo95/

The picture is calibrated with dark frame bias frame and flat frame all at -20 degrees.

I have this defect in all the picture and i can't adjust it.

Please do you have some suggestion?

Thank you in advance

please contact us through email: support(at)zwoptical.com

we would like to check your raw light and flat frame

Hello Mr. Sam

So i send a raw file light and raw file flat?

Yes, that's correct.