How is the extraction from the Ikea waste system correctly clicked?

Hello! After the moving helpers left, I am alone installing the large full extension for the sink cabinet. It is mounted, but I have already noticed that the waste system only fits in the cabinet if you do NOT install the second drawer, or rather the Rationell extension - MISPLANNING on my part, unfortunately. So I took out the extension again and only installed the lower extension. That is the one with the double part as the front, although I don't think it looks any better than if it were one piece. But I can't get the thing onto the rail! The rail is mounted in the cabinet as it should be (compared to already mounted extensions). Now I place the heavy thing onto the rail - it clicks in at the front, but it can be lifted at the back and therefore falls forward (due to the overweight of the extension) again. Did I mount something wrong or how is the extension correctly "clicked" into the rail so that it holds? And is there another waste system that also fits with the mounted, less deep extension, or does the thing have to stay out?

At the back of the rail there is a hook. It did not catch there because the drawer was probably slightly tilted. Try it like this: Pull the rails all the way out, place the drawer on the rail so that you can just see the hooks. If the drawer tilts forward, load it at the back. Push the drawer all the way in and make sure it clicks in at the front.

Thanks for the tip. Unfortunately, it hasn't worked so far. It's really difficult alone, but I also believe that I haven't understood something about the mechanism yet. When I try it the way described here, the drawer doesn't slide all the way to the back but gets blocked somewhere before.

Do you have a picture? Normally, it works the way the Ikea expert described...

Try instead of inserting the drawer, to reach under the drawer after setting it down and pull the rail and drawer together. Check if the rear hooks are not bent downwards. The sheet metal of the frame must be able to slide underneath.

Unfortunately no picture, I somehow don't know how to photograph it. I will try to install the thing with a strong man tonight and will report again then