halo 3 i need to know why when i get any of the silver skulls it doesnt show up

[colinmooret4r]

as an acheivment? am i still getting credit when i pick them up, put them down and save and exit the level
which silver skulls do
which silver skulls do have achievements

 

[Philip L]

like what the other person said ONLY SOME have achivements not all tho.

 

[xinic5]

not all the skulls have acheivements for them, that may be it.