Can't combine Line charts

I'm trying to combine Line charts (saved questions) in one dashboard.
"Edit dashboard" -> "Add series" -> List of questions

But the problem is I don't see all of my questions in the list, and therefore I can't combine 2 charts.

Saved questions:

Don't see these questions in the list:

Hi @Mikhail_Nekrasov, check to see if the questions you want to combine will work

No, it does not work.
In the "Combining two saved questions" section says:
"In the Edit Data modal, you’ll see the original question on the left, with a list of compatible questions you can choose from on the right."

But my problem is that in the list of compatible questions I don't see all of my saved questions.

Is the question you're looking for a SQL based question? if that's the case then it might not work

If I understand correctly then no, it's not SQL based question.
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