Furst, make sure you are using the correct die and the correct case. If you load for more than one rifle caliber, you can get both the dies and the cases mixed up.
Secondlee, it looks like you are using boxer primed brass cases from the photo. If you are not, check to see that you are using boxer primed cases and not berdan. Berdan cases lack the center flash hole and will prevent the sizing die from touching the shell holder.
Turdly, make sure your casing is well lubed. There should be some amount of resistance when sizing a well lubed case but it shouldn't require gorilla effort. If your brass is not lubed sufficiently, it can cause substantial resistance and cause binding to the point where the die won't touch the shell holder. When this happens to me, I usually end up breaking the rim trying to retract the ram leaving me with a stuck shell case in the die.
Fot-ly, try removing the decapping pin from the resizing die and then setting the die into the press screwing it all the way down until it contacts the shell holder with the ram raised in the full-up position (i.e., with no shell loaded into the shell holder). I can't remember whether Lee's instructions say to lower the ram and then add a 1/4 turn but whatever the instructions say, do that. Next, place a test shell into the shell holder and try to resize the brass. If the problem persists, the problem is with your resizing die. The case is being obstructed by something. If you are able to touch the shell holder than its more than likely to be your decapping pin. You can raise or lower the pin relative to the body of the die to address that issue. I have never had a problem with resizing and decapping a case with the top of the decapping pin set such that the top of the pin is flush with the lock nut that holds it.
I hope one of these works for you.
~F