I am trying to ads a second light fixture to a circuit to one line controlled by the same switch by feeding from the switch to the second light...Very frustrating! I added the new light in parallel but this does not work. The new light glows while the old light barely illuminates. We have a 70 year old house with plaster walls and I am trying to do this simply, without tearing up walls. Help. Thanks. Bruce Russell
You have managed to wire them in series, which is why the dimming. If the switch does not have a neutral wire then you will not be able to wire it from the switch.
What you want is the hot wire going from the switch to the fixture to be wired to the hot wire of the new fixture and the neutral wired to the neutral of the old fixture.
If the power goes to the old fixture and then they ran two wires to the switch you will not be able to feed from the switch. You will need to feed from the old fixture.