Dimension a diagonal unable to do this

How can I do a dimension across the diagonal corners of a rectangle? When I try to do this by selecting the opposite corners, it always moves away to an adjacent corner. What I mean is if you have a rectangle with vertices A, B, C and D, it is easy to do a dimension from A to B pr B tp C, but I cannot do a dimension from A to C. thanks, Vern

Like this?

You just have to pull the cursor out in the right direction.

And an animated version of Daves answer…

Yes, I got it to work by making sure I placed the dimension outside the square not on the inside as I first tried to do. The inference engine tried mightily to move the points to adjacent corners, but by putting the dimension outside the object instead of inside as I first tried to do, it did work just as you have shown. Guess I just get frustrated easily. thanks, vern