Hi William..!!
First -
Welcome to the LugerForum!
Second - on the last round fired from the magazine, will the toggle "stay open"? If not - either the ammo isn't quite strong enough to fully cycle - OR - if you have a really early Luger, it doesn't have a hold open, but most 9mms have the hold open
A quick way to test is - WITH NO AMMO IN THE LUGER OR THE MAGAZINE! - pull the toggle all the way back. Does it lock open?
Let us know which Luger you have, OK? There are a couple of other things that come to mind as well - but my first guess is that the Ammo needs a bit more "juice"...
Best to you!
John