using UI for doom clone weapons

What i'm trying to do is display the weapons using the worldspace ui.that way it can interact with the light and all.
now i can take the sheet and animate it in 2d mode however trying to get it to work as screenspace ui does not seem to work. i seem to be missing something in the process.

essentially i want the anim to play when certain buttons are pressed. I can get static images, and looping animations to work but cannot seem to get it with button press.