In view of the recent conversation about different ways of raising the poptop,
here's what has worked for me. I'm 5-7 (170cm), slight to medium build, and
now in my seventies, and have never had trouble raising the poptop, though it
should be noted that I do not carry anything on the roof.

Stand under the skylight facing the sliding door. Grip the lifting bar with
your right hand and place your left hand against the roof just forward of the
skylight. As forcefully and as quickly as you can, push up with your left hand
to the maximum extension of your arm and immediately drive your right hand
across your body toward the front of the van, turning your upper body as
needed to drive the lifting bar all the way home.  When these motions are
smoothly combined, the poptop does indeed pop right up.

My wife, who is 5-1, can execute this, but comes up just a little short to
drive the lifting bar all the way home, though she has succeeded at times.

Try this to see if it works for you.