Can't create pyramid from specific image

[sirjimjones]

Hi,

I am having an issue with the following code when creating a pyramid from this specific image: http://fs1.directupload.net/images/150921/y5oxhkvs.png

var imgDestination = Resources.test.ToArray() as Bgr[,];
var grayImg = imgDestination.ToGray();
TemplatePyramid.CreatePyramidFromPreparedBWImage(grayImg, string.Empty));

The last line returns a null value.

Any idea why this happens? Other images work.