Spectral data issue from KX134-1211 Sensor

[doludiranNano]

Hi I'm working with the KX134-1211 Digital Accelerometer to use in some vibration analysis application. I'm reading data from the accelerometer in synchronous mode. The issue is when I plot the spectrum for the data gotten from the accelerometer at rest, I see clear peaks at certain frequencies which should not be the case. I'm new to working with digital accelerometers but I've been through the technical specs and manual and I can not figure out what the issue is. SPI clock is set at 10Mbit/s with CPOL and CPHA both 0 and reducing the clock speed doesn't seem to help either. ODR is set to 25600. Please see attached my codes and some screenshots of the spectrum data. Any support on this will be greatly appreciated. thanks
kx13xcfile.txt
kx13xhfile.txt
main.txt