WHY CANT I DELETE OR EDIT MY POSTS?

[mayadmax]

i want to edit/delete some of the comments i made in threads...normally i see a edit button under my comment but in some cases i cant see that button..

How can i delete/edit them?
why cant i see that button

help

 

[ela_eluwa120]

there is a time limit to edit the posts i guess...
you can't edit or delete your too old posts...

 

[gn.karunarathna]

b cos u r becoming a admin? anyway there is a time limit machan.. if u pass tht time limit, u cant change tht...