Why is that happening? And what can I do to it to ask it again in a more acceptable way?
It doesn't seem to be on topic
The question exists on SO, a site we have very little content overlap with. While you acknowledge its existence on SO, you don't explain why you're asking on SU. Which leads to…
It is unclear what you want
The SO question is from the POV of the web site owner. Yours doesn't seem to be, but you're still calling it "cross-post", implicating it's identical. You post on SU when the original question would be unfit to be posted here. It's simply unclear what an acceptable answer would look like.
We consider cross-posting to be abusive behavior towards our community: Someone asks the same question on multiple sites at the same time to maximize exposure, and once an answer is posted for one of them, it's likely the other duplicates are left lying around, possibly unanswered, and the user doesn't not responding to follow-up questions. It's simply a mess.
However, what you did is not cross-posting: You're just asking a question someone else asked somewhere else. But you called it cross-posting, and it's possible others stopped reading at the first word and down-voted.