PROBLEM WITH N900V cert

this phone had 5.0 installed
initially i was able to reset msl and change cert without root

since then
i am trying to change cert again and it prompt to reset msl..i do reset msl but i keep getting reset msl error when i try to write cert

i downgrade phone to 4.4.4 and i get the same thing..i have installed nk1 4.4.4