Ikea Tupplur blind does not lock

Hello,

I have installed 2 Tupplur blinds in the bedroom. After setting the retraction height, I wanted to pull both blinds down, but one of the blinds does not stay at the desired depth (does not lock). Is there a trick or something similar (the other blind works perfectly)?

Regards Gallanz

Move a little toward you, so diagonally and somewhat jerkily. With us, it also often doesn't lock or doesn't retract all the way to the top.