Can't get magnometer data from LSM303 w/ Boron, can get Accel

I am using a Boron board that talks to a LSM303 using the adafruit sensor libraries. For some reason, I can get acceleration data, but I can't even get the magnometer to connect, but I thought they were the same device.

I am using the library: Adafruit_LSM303_U. here is my code:

Adafruit_LSM303_Accel_Unified accel = Adafruit_LSM303_Accel_Unified(55555);
Adafruit_LSM303_Mag_Unified mag = Adafruit_LSM303_Mag_Unified(44444);
sensors_t_event event;

if (!accel.begin())
    Serial.println("Could not find accelerometer");
if (!mag.begin())
    Serial.println("Could not find magnometer");


    // /* Display the results (acceleration is measured in m/s^2) */
    Serial.print("X: "); Serial.print(event.acceleration.x); Serial.print("  ");
    Serial.print("Y: "); Serial.print(event.acceleration.y); Serial.print("  ");
    Serial.print("Z: "); Serial.print(event.acceleration.z); Serial.print("  ");Serial.println("m/s^2 ");

    /* Display the results (magnetic vector values are in micro-Tesla (uT)) */
    Serial.print("X: "); Serial.print(event.magnetic.x); Serial.print("  ");
    Serial.print("Y: "); Serial.print(event.magnetic.y); Serial.print("  ");
    Serial.print("Z: "); Serial.print(event.magnetic.z); Serial.print("  ");Serial.println("uT");

in this example, the accelerometer data comes back, but it fails to find the magnometer in the mag.begin() step.

Is there some big mistake im making?