rear door speaker not working

Hi, since ive owned my disco the speaker in the rear door/boot has never worked, It doesnt have the original stereo in there and i was wondering if this could be the problem? Does it need to have the original LR stereo fitted for this to work (ive still got the CD multichanger under the drivers seat - this has never worked as niether have the dash mounted volume buttons) I know nothing about matters of this sort so please enlighten me. Thanks

ermm is it actually connected?

Dash mounted volume buttons work only with OE tuner ,check connections at rear of tuner,if there are any spare ones not connected (probably volume connectors)

"Does it need to have the original LR stereo fitted" NO what ever head unit u have it will need a pre amplified output, if it has then the backdoor bass speaker will work when connected and powered unless it's faulty that is.