Letterbox does not appear on mobile device

Hello, I'm trying to get letterboxing/pillarboxing to work in my game. It works fine in the unity editor, but when I build the game to Android the boxing does not appear, and some graphical artifacts are rendered in its place. These screen shots are from a test project that only contains an image and letter box code:

Correct version in the Unity Editor:


Incorrect version on android device:

(Notice the top and bottom sections of the screen)

Code:
// set the desired aspect ratio (the values in this example are
// hard-coded for 16:9, but you could make them into public
// variables instead so you can set them at design time)
float targetaspect = ASPECT;

// determine the game window's current aspect ratio
float windowaspect = (float)Screen.width / (float)Screen.height;

// current viewport height should be scaled by this amount
float scaleheight = windowaspect / targetaspect;

// obtain camera component so we can modify its viewport
Camera camera = Camera.main;

// if scaled height is less than current height, add letterbox
if (scaleheight < 1.0f)
{
Rect rect = camera.rect;

rect.width = 1.0f;
rect.height = scaleheight;
rect.x = 0;
rect.y = (1.0f - scaleheight) / 2.0f;

camera.rect = rect;
}
else // add pillarbox
{
float scalewidth = 1.0f / scaleheight;

Rect rect = camera.rect;

rect.width = scalewidth;
rect.height = 1.0f;
rect.x = (1.0f - scalewidth) / 2.0f;
rect.y = 0;

camera.rect = rect;
}

Any thoughts on this?