In order to ensure that the sequencing quality is not affected by a technical failure, an internal quality control is performed with each sequencing run. In addition to that, a sophisticated software is analysing each plate considering parameters like quality values (QV) and reading lengths.
If you see "DONE_QV_NOT_MET" as a result of your sequencing reaction, it means that the internal quality control has passed, but some sample quality values have not been met. (e.g. sample or primer concentration or volume, sequence design or structure etc.).