colorAtTouchPoint always returns 0,0,0

I was playing with the ColorObjectTracking demo and noticed that the color doesn't change when I touch the screen. However, I can change the threshold by dragging the finger.

I delved deeper and noticed that colorAtTouchPoint from GPUImageRawDataOutput always returns 0,0,0 (r,g,b). I also noticed that this:

[videoRawData setNewFrameAvailableBlock:^{
        if (shouldReplaceThresholdColor)
        { //code }
}]

is not called after initialisation so after a screen touch there is no code that actually changes the color being tracked. I'm only new to GPUImage and Objective-C so I could be missing something.

But yeh, main problem is I can't change the color being tracked.