I'm not sure what bike you have, but on a Heritage in order to evenly lift the bike the jack has to be on the shocks.

Below the first picture shows my Sears yellow jack position and my Redline dolly position.
My yellow jack has a 12" spread on the pads and my Redline dolly has a 23"+ spread.

As you can tell my jack is on the shocks.




This picture shows the bike on my Redline dolly.



The next two pics shows my Redline dolly is outside the shocks so there's no pressure on them.

 

On my '03 Heritage softail, with both my old Craftsman jack and my J&S Jack, if I want the bike to be balanced, one of the runners has to go across the bodies of the shocks.

If I try to lift it without crossing over the body, it's pretty tippy......

 

+! ---I've posted the same thing Many,Many times over the 9yrs I've been a member in here....
Except I use 1/4 inch thick Heater hose pieces about 7-8 inches long split length way and leave them on the bike all the time..

 

Mines a Deluxe and its balanced on the lift w/o being on the shocks. Maybe its the lift I have....

 

My Son has a 16 Slim and he puts the jack just in front of the shocks , the front comes up a little. Before the rear but the bike feels stable .