MPU3300 Z-axis doesn't work well

Hello,
I develop a stabilization platform with the MPU-3300.
Response of the X Y axis and temperatur sensor looks ok. At Z axis there is only noise.
I use I²C my approach:
Address: 210

Read(0x75)           // Who AM I         Check - Response 0x68

Write(0x6B, 0x03);	// PWR_MGMT_1	    PLL with Z axis works (others too)

Write(0x1A, 0x00);	// CONFIG	        8kHz

Write(0x1B, 0x00);	// GYRO_CONFIG      225°/s

Write(0x6C, 0x00);	// PWR_MGMT_2	    No standby

Write(0x19, 0x09);	// SMPRT_DIV        Output-Rate: 800Hz



// Read out data:

//X-axis

read_h = read(0x43);

read_l = read(0x44);

x_value = ((read_h<<8) + read_l);



//Y-axis

read_h = read(0x45);

read_l = read(0x46);

y_value = ((read_h<<8) + read_l);



//Z-axis

read_h = read(0x47);

read_l = read(0x48);

z_value = ((read_h<<8) + read_l);

Have you any ideas why it doesn't work well?