How to properly install extendable Ikea curtain rails?

Hi Ikea fans,
I hope to find someone here who can explain to me how to screw the "Mitnehmer" onto the curtain rails.
To explain: the curtains hang in such upper and lower rails and at the front and back, such small, gray -- I'll call them Mitnehmer -- are supposed to be screwed on so that the first rail takes the second with it and the second the third etc. etc. But when I screw them in tight, they sit too far inside the rail and cannot reach the next rail to "take it along." What am I doing wrong?
I am grateful for any idea!! :D

Hello, images showing the problem could help with the error analysis.

Hello IKEA expert, thank you very much for the quick response! But in the meantime I was lucky enough to be able to ask a Kvartal-knowledgeable neighbor and the curtains are hanging! :D :D