Never buy any batteries without date codes. You probably got some 6 year old ones at the dollar store.
On a 9V batt the date is on the bottom. Mine are "fresh" and will last many years because the meters draw such tiny current. They actually come from a mammoth B to B wholesaler in CA who receives boatloads from China... not from a 99 cent store.
Meters, of course, are calibrated and tested before shipping - so of course the battery "works". I did find one dud out of ~22000 over the last decade.
