I can't figure out the measure function. I select the object (a line or arc) as it asks, then hit enter. From there I've tried entering a number or clicking either endpoint of the line. Nothing works. 
  
I'm trying to divide the line up into segments so I can put tick marks to designs 100'. How can I do this? 
  
Thanks. 
  
Command: pedit 
Select polyline or [Multiple]: m 
Select objects: 1 found 
Select objects: 1 found, 2 total 
Select objects: 
Enter an option [Close/Open/Join/Width/Fit/Spline/Decurve/Ltype  
gen/Reverse/Undo]: j 
Join Type = Add segment 
Enter fuzz distance or [Jointype] : 
0 segments added to polyline