when I try making aligned dimension, I can't draw it exactly.

[joe-2020]

When I make the aligned dimension, I can see the blue line on the wall(first wall) at first. But when I tried clicking another wall (2nd wall), I can't see the blue line which means I can't snap on the wall exactly. How can I solve this problem? Thanks

[s.borello]

You can draw a couple reference planes then dimension to those... they will not plot. 

[barthbradley]

sounds like the wall is askew to the view.  

[joe-2020]

I will check

[ToanDN]

The walls are not parallel. Fix them or use tab to snap to an endpoint. Did you create the walls based on a cad file?