R730xd - CBL0009: Backplane 0 connector A0 is not connected (rear flexi-bay drives)

Hi have a R730xd and have installed a back-plane card part #6WNVX for the rear flexi-bay drives.

However on boot, whilst the PERC H730 finds the drives at the front, it is unable to find the drives at the rear and i get an error:

CBL0009: Backplane 0 connector A0 is not connected.

UEFI0116: One or more boot drivers have reported issue(s).

Check the Driver Health Menu in Boot Manager for details.

Controller: VenHw(C153B68D-EBFC-488E-B110-662867ABCDEF)

  CBL0009: Backplane 0 connector A0 is not connected.

Have attached cables as per below:

Thanks in advance, config below if useful: