Mattitude nailed your issue.
Back that die body off until no crimp is being applied, and then crank just the seating stem down until a bullet is seated to proper depth.
Now back the seating stem clear out, and slowly crank the die body down until you have a light crimp. Lock the die in place at this point.
With the die body locked at the right depth for your crimp, put your test round in the shell holder and raise the ram. With the ram up, crank the seating stem back down until it hits the bullet. Lower the ram and add 1/16-1/8 turn deeper. Lock the stem in place.
Now try seating and crimping again on your newly adjusted die.
Or, get a Lee factory crimp die and seat in one step and crimp in the next.