BAFFLED - Unipolar Output to BiPolar Amplifier???

[Majorassburn]

I'm baffled and confused.  A Mind Block    HELP ME PLEASE.

Here's my dilemma:
1)  I have a subassembly with an on-PCB single 12VDC power supply. It generates a unipolar 1KHz, 2Vrms, ac-coupled output sine wave referenced to its circuit ground.
2)  I have to amplify that 2V sine wave to approximately 6Vrms.
3)  I have another subassembly with an on-PCB dual +12 /-12VDC power supply, ac-coupled input to an op-amp x3 inverting amplifier which could output a 6Vrms bipolar ac-coupled signal referenced to its own circuit ground.
4)  Both subassemblies must share the same common circuit ground.

Problem:
The unipolar 2V output from the first subassembly is processed and output by the second subassembly but only as an amplified UNIPOLAR signal rather than a BIPOLAR signal.  (Unipolar swings from +12V to Ground. Bipolar needs to swing from approximately +9V to -9V, about 18Vp-p, above and below Ground.)

What am I missing here? Thanks in advance for suggestions or solutions.

[Kim Christensen]

Faulty/leaky coupling capacitor between the 1st amp pcb and the 2nd one?
Post a full schematic of the entire set up.

[Konkedout]

As Kim said, we really need to see a schematic diagram.

But it is not strictly necessary to AC couple the signal to take a unipolar signal into a bipolar powered op amp and get a bipolar output.  This can also be done with proper biasing.  And there is some chance that the op amp may be set up to do this, but you defeated the purpose by AC coupling the input signal.  (??)

[Majorassburn]

Schematic on the way............