I purchased the rear sight tool on your web site - Item Number E00457 - and am having difficulty installing my new adjustable sights on my Px4 and 90-Series pistol. What is the problem

PX4 Adjustable Sights

The sight tool is designed for the removal and installation of fixed sights on these types of pistols.  If you install adjustable sights, partial disassembly of the sight is required to remove the tool.  We recommend that if you intend to install adjustable sights on your Px4 or 90-Series pistol, that you have a competent gunsmith install the sights for you.