What LED?
Why are both outputs show as 2.5V?
If you have Key = Space for both U6 and U7, the how do you change only one input?
Please remove the unnecessary jog in the bottom wire to U2's input. It makes your schematic look amateurish.
Show the complete circuit if you want a learned answer.
If this is a simulation, do not define the outputs. If it is an actual circuit that was built, give us the device numbers and pin numbers. AND I see no LED at all, so we are oly shown a partial circuit.
I no longer provide assistance for partial circuits.