The ObjectDetect module http://jevois.org/moddoc/ObjectDetect/modinfo.html
has several parameters you can tune if your objects are not detected with the default settings. The default settings assume that your object has unique texture elements, and will not work well with objects that are very simple, e.g., a white square object.
First try higher "distthresh". This is how similar keypoints must be between learned image and current image.
Then try to broaden the range for "goodpts", this is how many matching key points are needed between learned image and current image.
Then try to lower "hessian" which controls how sharp keypoints have two be to be considered.