Will Eye Tribe work correctly when the device is vertical?

[metaphase]

Hello,
I am using Eye Tribe with Surface Pro2 and I am satisfied with the eye tracking result when the screen is horizontal (Landscape mode), however, when I try to rotate my device and work under Portrait mode (which means, the device is vertical) it seems that the tracking result will become poor even the calibration result is Perfect. For example, the cursor will be shifted randomly.
So I wonder whether designers of Eye Tribe have considered the operation of Eye Tribe when the Surface Pro2 is under Portrait mode (I can only find demonstration for horizontal screen on http://theeyetribe.com). Or the poor tracking result is just due to my wrong operation and someone has found their Eye Tribe worked correctly even if the device is rotated? I would be grateful if you can answer my questions briefly.

[Javier]

The Eye Tribe Tracker is designed to work when placed horizontally, and will not work if placed vertically. If you'd like to use the Surface in portrait mode, you'll need to attach the device on the side of the screen that remains on the bottom, and calibrate when in that position.

[metaphase]

The Eye Tribe Tracker is designed to work when placed horizontally, and will not work if placed vertically. If you'd like to use the Surface in portrait mode, you'll need to attach the device on the side of the screen that remains on the bottom, and calibrate when in that position.

Sorry for the confusion, when I said "device", what I mean is the Surface Pro 2
Thank you very much, I will try to adjust the Eye Tribe and Surface Pro2 according to your advice