You must have a patient ground connected to the amplifier. This can be through the green safe touch connector on any one of the headstages attached to the amplifier or it can be directly connected to the green safe touch connector on the amplifier manifold. Your options for reference connection is to either connect the reference to the red safe touch connector on the headstage (this is recommended) or to use a reference from a different bank of channels by setting the DIP switches on the manifold (typically only recommended if you have a bad reference or as a last resort). The dip switches are explained in the attached IFU. Please verify that your DIP switches are correctly set as this will determine which, if any, reference is used.
-Ground in the headstage is directly attached to the amplifier ground through two redundant wires in the blue ribbon cable (pins 37 and 38). Reference is buffered in the headstage and then travels through two redundant wires in the blue ribbon cable (pins 33 and 34).
-Shielding in the blue ribbon cable is attached to the amplifier ground on the amplifier side of the cable and not connected to patient ground on the headstage side