What would cause it to leak from the TOP of the nut? And how to fix(02)

What would cause it to leak from the TOP of the nut? And how to fix(02)

Image gallery: Nutcleaning Leaks

Leaking Packing Nut Repairs - 3 Tips to Repair Valve Leaks This leaks from the top of the nut. What can I do? : Plumbing What would cause it to leak from the TOP of the nut? And how to fix