back speaker trouble

[Gene4running]

I am new to this place and i just got my T4R like a week ago. its 1995 limited and i just put in a new HU and everything is working fine. but when i play things from a CD or Bluetooth or AUX only 4 of the 6 speakers play. the 2 that don't play are the lower back speakers. but when I put my HU in radio mode it plays 6 of the 6 speakers.. any clue?

Thank you!