Regarding the angle calculation through ADXL313

Hi 

I am developing a tilt sensor for that I am using ADXL313.

I have some confusion regarding the calculation of the angle of X, Y and Z.

I am using this formula to calculate the angle of x y and z. and for the firmware I  using the ARM-Mbed platform.

please take a look---------------

FltAlgX = asin(DataX[0]/65536)*Rad2Deg;
FltAlgY = acos(DataY[0]/65536)*Rad2Deg;
FltAlgZ = asin(DataZ[0]/65536)*Rad2Deg;

(Rad2Deg=180.0f/3.141592f)

I am dividing the data of x y and z from 65536 to convert it from 16 to 10 bit.

After calculation, my result is like this-

2176, 2112, 32704, 1.86,88.18,29.94

2176, 2048, 32704, 1.87,88.18,29.94

2112, 2176, 32704, 1.87,88.17,29.94

2112, 2112, 32704, 1.87,88.16,29.94

2304, 2176, 32704, 1.88,88.16,29.94

2112, 2048, 32704, 1.89,88.15,29.94

2176, 2048, 32704, 1.89,88.17,29.94

2240, 2112, 32704, 1.90,88.17,29.94

2176, 2112, 32704, 1.90,88.17,29.94

2176, 2176, 32704, 1.90,88.16,29.94

2176, 1984, 32704, 1.90,88.16,29.94

2176, 2240, 32704, 1.90,88.16,29.94

2240, 2112, 32704, 1.91,88.15,29.94

2176, 2240, 32704, 1.91,88.14,29.94

2240, 2048, 32704, 1.92,88.13,29.94

2176, 2304, 32704, 1.92,88.13,29.94

2176, 2048, 32704, 1.92,88.12,29.94

2176, 2176, 32704, 1.91,88.13,29.94

2240, 1984, 32704, 1.92,88.14,29.94

2176, 2112, 32704, 1.92,88.15,29.94

2176, 2112, 32704, 1.92,88.15,29.94

{The first 3 are the reading of x y and z and the last 3 are angle of x y and z}

coming to the question my problem is I am confused that is this data correct and when I am tilting x axis the y and z should be zero but it is not like that constantly the give the value of 88 and 29.

Can you please suggest me where I am doing the mistake?