Canvas override Sorting causes errors

Hi i want to know if some of you guys have a solution to a problem i am encountering.

I am using the unity GUI and getting errors if i am doing something like this:

[36934-bug+report.png|36934]

To put it in words, i have 2 Canvas one inside of another one overriding the sorting, and below the second canvas i have another ui element. I will always get the errors you can see in the screenshot.The good part is it still seems to work just fine. I found no problem with the ordering. It also seems to give the error when exiting the game from playmode back into the editor.

Update: It also seems that the buttons are not clickable anymore.

Am i doing something wrong or is it just a already known bug?

Thanks in advance

KeySam

For now to avoid the errors and some other weird behaviour i encounered i am using sprites for layering, but using recttransforms for size (having a script to adjust the size).

If anyone has a better solution please let me know.