Make sure you have the spring and bottom plate pointed in the right direction, and the bottom plate against the spring. Push the spring into the magazine with the bottom plate, then slide the retainer plate over the bottom plate and make sure the raise area clicks into the opening of the bottom plate.

I'm sure my titles of the pieces is not correct, and just going from a poor memory on the procedure. It works on a similar pistol for me.

Have a blessed evening,

Leon