That symbol just doesn't exist on the new MacBook Pro keyboards, since Apple entirely removed the numeric keypad.
You can remap the command to a different shortcut, get an external (USB) numeric keypad, or even use an iPhone app to turn an iPhone into an external numeric keypad.
There are instructions for remapping keyboard shortcuts on
this page.
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Todd Kopriva, Adobe Systems Incorporated
putting the 'T' back in 'RTFM' :
After Effects Help on the Web
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