How do you verify the accuracy of your meter and what is your calibration process. Unless the meter you purchased is a high end meter your statement that it is very accurate is at odds with all that I have been able to research.
I've used the cheap (analog) radio shack meter for years doing a poor man's RTA on my car audio system, and have never taken lower then second place. (frequency spreadsheet, test disc, and patience) The results with that compare very closely to a professional RTA also. (used to buy rta time before events, until I figured out how accurate the radio shack method was...)