There appear to be bugs in FitDay's computation of micronutrients. Compare labels to the Total Nutrition values for the same food, and there are even bigger discrepancies.
When the FitDay and label values disagree, the label will always be more accurate. Manufacturers will change their formulations regularly, and the nutritional info will very considerably from one company to another. They're only allowed to fudge by 20% or so on labels, but FitDay may have very old data.