The answer is simple... find the nets "OUTPUT" and "SUPPLY" on the nets +5V and GND and change them to the net they are connected to, +5 or GND. Did you mix 2 schematics?, that's a common error, I've done it many times. When you attempt to put 2 schematics together, run the ERC on the schematic. This will help you resolve any net errors created when pasting schematics together.. and any other common errors like unconnected GND or +5 pins on IC's and un-intentional connections like your net issues, Shorts too..
Bob
{Edit RKJ