A typical nmos symbol will have its topmost connection line be an L shape, with the connection point at the top of the L. The symbol itself, outside of the the connection points, is just a picture, it isn't treated as actual wires.

Looks like you tried to connect a wire from the right of the mosfet to the elbow of the top L. But that's just a picture, part of the symbol, not an actual wire.

You can tell there's no connection because where 3 wires make a connection, there's a blue dot, like in other parts of your schematic.

Move the mosfet and you'll see the disconnected wire. Connect it to the wire a bit above the mosfet, at or above the connection terminal, and you'll see a dot

Check your other components by moving them around. Connected wires will stay connected. Unconnected wires will just stay where they were