The error stems from that map not having a background color.

This might immediately sound a bit weird, but in CC3+, a bacground color is associated with an actual entity on the BACKGROUND layer, while the color you see in the map isn't the background color, but the view window color. One way you can see a difference between the two is that a background color is only behind your map, while if there is a different view-window color, you'll see it behind the symbols in the symbol catalog window as well.

In short, you don't want to use the Change Background color on that map. You'll want to use change properties to change the color of the coastline, and View -> View-Window Color to change that dark "background" color.

Let us have a look what hides beneath the surface of our neighbor, shall we?

As always, you can see the time in your timezone in the left sidebar. You can visit the stream over at YouTube if you wish to participate in the chat.

The rotation commands allow you to type in the exact amount on the command line. I recommend the non-visual rotate for these operations, which you find by right-clicking :CC2ROTATE:.

Or, if you have a Norwegian keyboard, you'll actually have an 'Æ' key on your keyboard :)

Check your sheet order. Your floor is most likely on a sheet that appears after the symbols in the list. Use the List command from the info menu to check which sheet your floor and the symbols you are trying to place are, and adjust the ordering accordingly. Remember that stuff on sheets at the end of the order appears on top of things from sheets higher up.

It is also possible that the sheet order is wrong and your symbols go to the wrong sheet. But this will also be revealed with a use of the List command. If the symbols are on the wrong sheet, use :CC2MCHANGE: on them to move them to the right one.