Shelly em attention measuring!

For a long time I was looking for a problem why the measurement is getting worse. During installation, you must install the L contact on the shellys at the same stage as the measuring sleeve. Otherwise, the values are displayed incorrectly.

is it possible, that this could also case, that for me, everything looks ok (i can connect device, i can operate switch...), but still the measured value (kW) are zero ?