Accelerometer class - isn't reading zero at rest?

[oddjob]

Do we have a bad KoP board or the code is wrong or missing some setup?

...

// Declare variables for the 3 axis accelerometer (2 channels wired)
Accelerometer *m_accelerometerX;
Accelerometer *m_accelerometerY;

...

// create accelerometers
m_accelerometerX = new Accelerometer(2);
m_accelerometerY = new Accelerometer(3);

...

//m_accelerometerX->SetSensitivity(0.0);
//m_accelerometerY->SetSensitivity(0.0);
//m_accelerometerX->SetZero(0.0);
//m_accelerometerY->SetZero(0.0);

...

accX = m_accelerometerX->GetAcceleration();
accY = m_accelerometerY->GetAcceleration();
...

The accX and accY values are about 1.5 each when the board is at rest. Do we need to use SetZero? I tried putting in 1.5 for the value and then accX went to an entirely different non zero value, -2.5 or something like that. Can I just use AnalogChannel and do the scaling in the code?