Help 73 pickup radio install constant wire loosing current?

[73beast]

1973 k20
installing a radio, all is ok until im trying to hook up to Yellow constant battery+ wire. I found an orange wire from the fuse box that had power with the key off so I tapped in. hooked it up to the radio and nothing?? So I tried the orange wire off the cigarette lighter tested it first and it also has power, so I ran the wire and hooked it up to the radio and nothing again..

I got to the point where I have my test light and holding it on each of the orange wires I extended and they are getting power but the second I hook it to the yellow wire on the radio they stop getting power and the test light shuts off.

what is happening here I have never experienced something like this. any help please!

also side note I just connected the yellow wire on the radio to the red wire( Key on voltage) for the mean time and the radio works good just does not save any presets as expected. so I do not think there is any problem with the radio.


Again thanks for any help