Hi John,

Thanks for replying. I did not change a few 2 prongs outlet to Leviton GFCIs without grounding wiring connected as there are none ground wires in the boxes.

Wiring is correct: Hot-black and neutral-white on the "Line" end.

But GFCI outlets cannot be "TESTed" or "RESET" with the two buttons on the GFCI outlets. The GFCI outlets are providing electricity and and green light indicators are on. A handheld wiring tester shows that the outlets are "Open Ground" (as there are not ground wires in the boxes) and cannot be reset as well.

Is it ok? Thanks for advise!