Please allow to calibrate a measurement with the drawing.
I usually get drawings completely off-scale and the only way of getting a correct scale is trial and error changing values within "Change Scale Ratio and Precision" box.

We could:
Select option "Calibrate measurement", draw line in the drawing over known distance, enter the length the line represents.
This will allow to calculate the scale and set it up with usually acceptable tolerance (definitely better than trial and error)...