Grease gun problem

[wrndln]

This is kind of model A related. I have had problems with reloading the cartridge in a modern grease gun before and now again. My grease gun was working OK until it ran out of grease. I reloaded the grease gun and now when I pump the handle no grease comes out. In the past I have had the same problem but after fiddling around with it for a while, I somehow got it to pump grease. By my age, I should know how to get the gun to work after reloading it, but I don't need to reload it very often. The cartridge is installed correctly and the pull tab seal is removed. I pumped the chrome plunger in and out on the bottom a few times, but it did nothing. If anyone knows the trick to get a newly reloaded grease gun to start working, please post how it is done. I attached a couple of pictures of my grease gun.
Thanks

Rusty Nelson