Motorsagemann

I purchased a Garmin Colorado because it was Wherigo compatible. I have found that, with many Wherigo caches, the Colorado doesn't "zero in" at a given stage. It will clock down to as low as 1 or 2 feet, but, never zero in and open the stage. It has done this at a variety of Wherigo caches. Has anyone else ever experienced this and can offer any suggestions to correct? Thank you, Motorsagemann