Bought a HMC5883 and MS5611 Board via E-Bay couple of Days ago from you.
The Baro works fine in Multiwii 2.2 but with ne Magneto plugged in its getting I2C- Errors and no Signal reading.
Changed SCL and SDA already, tried Pull-Ups and at least ordered a second Board from you, with the same result.
Now I take a look with the Serial-Monitor both have a Unknown error on I2C 0x1E, Baro and MPU looking fine.
Do have an Idea to Fix that Issue?
Maybe the value of resistance is not correct for your system.
We can test your boards if you want. You have just to send us them.