I am using a Mac so I downloaded DraftSight 2018 SP2 today because my previous version of DraftSight suddenly stopped working correctly. Now I can not get the SMARTDIMENSION feature to work. Here are my actions:

1. I select SMART from the top menu labeled "DIMENSION"

2. I select the line that I want the dimension

Result: An "X" appears on the line. No dimension is provided.

Here is what is showing in the Command Area:

_SMARTDIMENSION

Specify entity to dimension or point>>

1 found

Specify another entity or point

0 found

If I a few times and play with a few other commands and then try SMARTDIMENSION again, sometimes it will actually produce the dimension on the drawing. I can not see any reason why this feature will only work part of the time as I am doing the same actions each time! (And this was how the feature worked on earlier versions of the software.)