[L3G4200D Gyro] Can't enable HighPass Filter

Hi,
i am using the L3G4200D MEMS on a GY-80 board.

My problem is, that i cant write data to a specific register.
I try to enable the Highpass filter on the Gyro.

So i write the following byte to the register:

I2Cdev::writeByte(devAddr, L3G4200D_RA_CTRL_REG5, 0b00010010);

L3G4200D_RA_CTRL_REG5 = 0x24

0b76543210
0b00010010

4th bit to enable HighPass Filter
1st bit to enable High- LowPass filtered Output

And when i read the register i get only 0b00000000.

Am i missing something or do something wrong?

Writing Data to the other register eg. L3G4200D_RA_CTRL_REG1- L3G4200D_RA_CTRL_REG4 is no problem.