ADXL335 vs.BMA180 for calibration

I have the problem with "Voltage to g" conversion for ADXL335.

Like reference device I use BMA180 Digital Accelerometer fixed in the same object and same axis orientation like ADXL 335 (see pict.''ADXL335vsBMA180.jpg'').

I receive a courbes and I see that initial g value of digital sensor not correspond to recalculated from tension g value of analog sensor

figure untitled_x.jpg shows that initial static value is not correct.
figure untitled_y depicts that initial static and dymamical values are not correct.
figure untitled_z seems correct.

Any ideas ?

Sincerely yours