Arc dimensions in 3D wire drawing

[Lentezza]

Hello,

I use Cad for Mac 2011. I was never trained in using cad-programs, so I have no idea (about naming things with correct terms)...

I have the following problem: I made this "3d"-wire drawing to find out the angles of an object. Now when I make an angular inquiry the value given is right. When I try to put in an angular dimension it does not work. I put in a screenshot here to be more clear. This is the situation viewed from southeast:

Agular dimension.jpg

So, the angle I want to put the dimension to is the one between the red lines. When I choose "Angular Dimension" and then pick the two lines the dimension is automatically put on the two white lines next to the red lines. While the verteces of the dimension lay on the picked red lines the arrows point to the white lines and the value given also refers to them.

What am I doing wrong?

[Dadgad]

Do you have an icon at the bottom center of your screen which activates and deactivates, or is there such a thing on the Mac version as SELECTION CYCLING?
On the PC version you can also cycle this option on and off with CTRL+W.

If there is, that would help you to ensure that your angular dimension is referencing the correct lines.
What perspective are you in when DIMENSIONING, TOP?

[nestly]

AutoCAD dimensions are always drawn on the XY plane of the current UCS, and they do not account for any changes in elevation (delta Z) You probably need to align the UCS with the two "red" lines prior to placing the dimension.

[Lentezza]

thank you for the answers. (Wrote another post before but appearently didn´t send it correctly...)

Nestly´s answer was the one.

Have good day!

[designerstuart]

Nestly´s answer was the one.

it usually is