Problems with make window hole in a wall

I´m trying to make two new windows in a 3D model recieved from others, but it just doesn´t work. I start drawing a rectangle on face of the wall. Then move it to right position. No problem. Now I choose the push/pull tool and grab the rectangle to move it into the wall. When doing so I can make a box both on the facing side and the other, but I can´t manage to make it a hole. I have tried to click on “the edge” of the existing window besides, but witout luck. When just grabing the rectangle and moving it forth and back edges inside the wall doesn´t show.
What am I doing wrong? I have watch the tutorial video on the subject several times without getting more enlighted (the wall is a parallel structure, so that´s not the problem).

Can anyone get me on the track of cracking the issue??

Sounds like you are working in the wrong context. The wall is most probably a group, double click it to open it for editing, then draw on your rectangle and go from there.
Or attach the model so we can see what you have.

Okay, I will try that. Thanks!

Is the wall inside a group or component? If so you have to open the group or component for edit before you can alter its contents. If you don’t do so you can still draw in the same location in space without actually cutting the window hole (SketchUp does not do collision detection; two objects can overlap if in different contexts).

It´s a group I see now. It´s an outerwall around the whole building.

Juhuuuu, thanks!!! I´ve tried so many times to make it work without luck. Now there are two fine windows in the model :-).

I´m happy!