Apple 30-pin Bluetooth Receiver w/ Polk audio speaker

Hi. I have a Polk Audio Speaker which has a 30-pin apple connector and is compatible with iPod nano 1st gen (and its linear generation of iPods that time). Then, I bought a Bluetooth (5.4) Receiver 30-pin Apple connector. Tried connecting them together and it doesn't work. But the receiver works if it's connected w/ just 30-pin to USB (just to know it's not defective)

Just want to confirm (an electronics type of question), if there's a different pins layout for the iPod nano gen 1 era compared to the succeeding iPod/iPhone gen's that has the same connector.