Dollar Tree

I worked at the dollartree( 65 Lawrenceville GA 6786940006 )January 2016 to October2016... I gave a notice, wored, and left for the military October2016... I can home about 2 yrs later and had the manager file a Officail MILITARY LETTER OF REFERENCE for me on August 2018...a week ago 8/2019 I applied to a different dollertree location(WESLEY Chapel road Decatur GA 7705806626 manager CLAY) only to be told I was ineligible for rehire...the only time I had a problem at the location I worked was when I was sick and I brought in doctors documention for this period...the manager asked me to come back and work for her during that time I had her file the military LETTER of reference...so if your sick and you bring in documentation is this grounds for ineligible for rehire, with an outstanding work reference completed(2018 almost 2 years later)?...im confused... As I still have thea copy of this official military LETTER the managerfile, signed, and dated they I submitted to the United States Navy... How can this be? Is this some kind of Federal offense, is the manager upset that I can't work at her location? Can someone explain