Accelerometer Sensor

[Pesticida]

Hello,

I make a Accelerometer Sensor Circuit for a Elevator,and I'm using a ADXL311J with a Rail to Rail OP Amp (AD6809) and 5 Volt Ref,50 Hz Bandwith with 0.1uF.
When I read now the Data on The Pic Microkontroller I see just a very little change,for Example :

when the Sensor is Idle I Read 130 thats mean I have 5 Volt/256 = 0.019mV per Unit then I have 0.019*130=2.47 Volt
2.413V-Vref/2=-0.03V
-0.03V/0.312V=-Acceleration 0.096g

Ok now when the Elevator is in movement I can Read the value 131 thats mean like the Formulas on the Top I have -0.035g Its this possible or I make somewhere a mistake?!

Thats mean i have (-0.096g) - (-0.035g)=0.061g
-0.061g*10 Seconds = Speed -0.61 Meters in 10 Seconds

-0.61 * 10 Seconds = Distance 6.1 Meters

Thank you for any Information

Regards Pesticida