Screen overlay when using hotkey to switch keyboard input

I've recently upgraded iMacs the other day. Can't figure out how to toggle the following overlay to show up when switching inputs using keyboard hotkeys

Right now the shortcut will toggle the input switch, but doesn't display the overlay below.

EDIT If it helps any I am using the first gen 27" Retina 5k iMac with Yosemite 10.10.1.

Solution 1:

In the Keyboard system preferences panel, select the Shortcuts tab then the Input Sources entry on the left. Enable the "Select the previous input source" checkbox and assign it to the keyboard shortcut you wish.

The input source switcher window ONLY works with this shortcut. It will not show if you use the "Select next source in Input menu" shortcut.

I'm guessing that the 2nd shortcut was added later by another developer. Besides the lack of this secret switcher feature, notice the wording of the shortcut description. If the same person did both, they probably would have called it "Select the next input source".

Solution 2:

I don't know what your set shortcut is, let's say it's control + space. Simply hold down control, press space but don't release control. The overlay will be shown.

Also, there's no need for three input sources. I have two input sources and it works.