no println out of setup - function while including i2cdevlib.h and mpu6050.h

[mga]

hello,
i just started using an arduino due together with a GY-521.

i copied the scratch from

https://github.com/jrowberg/i2cdevlib/blob/master/Arduino/MPU6050/Examples/MPU6050_raw/MPU6050_raw.ino

and included the i2cdevlib.h and also the mpu6050.h via Sketch, add file within the arduino ide 1.5.8.
But in the serial monitor i don't get any info (i've changed the baud rate to 9600 in the code, because the serial monitor doesn't have the possibility to set it to 38400).
not including the h-files, mentioned above, i get Serial.println - information out of the setup - function.

is there anyone having an idea? thanks in advance.

cheers,
mario