Audio electrics

Question

Hi I have a year 2002 VWLupo 1500cc Auto . It is fitted with a "Beta/Gamma" vw radio cassette . I baught a Gamma Single play Cd unit (Ebay) which can be fitted below the rado/ cass by removal of a glove shelf .The unit came with one fitted loom cable which plugs into rear of exsisting radio i presume to pick up 12 volts and input to radio for amp/spkr etc., When plugged in unit is dead as a door nail ! From looking at cd rear there is another 2 socket points ? Do I require More inter unit connections than the single loom/plug which came with the unit ???
Kind Regards Bernard