NHD-C12864LZ-FSW-FBW-3V3 correct Vout voltage

[Spero]

Hi...

I'm using a NHD-C12864LZ-FSW-FBW-3V3 LCD with the following configuration:
  Vdd=3.1V
  1uF caps on the CAPxx and Vx pins (4 x voltage booster circuit)
  SPI mode
  /WR, /RD and C86 = Vdd
  PS = 0V

After initialization, the Vout pin = 1.44V whilst the Vx pins are all lower than this (~1.3V)

What should the Vout pin voltage be - 1.44V seems too low?
The display is completely blank after setting the all points on command (0xA5)

Thanks,
Spero