Copying formulae across rows shift their cell information incorrectly?

[ChristopherMR]

Using LibreOffice Calc 6.3.

Setup:
A1 = 1; B1 = 2; C1 = 3; D1 = 10;
A2 = 1; B2 = 2; C2 = 3; D2 = 100;
A3 = 1; B3 = 2; C3 = 3; D3 = 1000;
A4 = A1 * D1; B4 = B1 * D1
A5 = A2 * D2

Issue:
As expected, when selecting both A4 and A5 and then dragging the handle down to A6, the result is A3 * D3. However, when selecting A4 and B4 and then dragging the handle across to C4, the result is C1 * F1, which seems to have shifted the formula from A4 to two cells to the right, when I want C1 * D1. I can copy a chain of formulae to continue that chain across rows, why not columns? How can I get what I want?

[eeigor]

Fix the $D column in all formulas (make the reference absolute $, e.g. $D1).

[Wanderer]

Don’t select 2 cells, only b4 before you drag. And fix d1 with the $ as @eeigor already suggested $D$1 or $D1