Feign Death Question

[Wrathis]

Hey all,

I have a quick question about FD. As of right now my FD is maxed for my level at 29.

Why does my FD fail without getting the fallen to the ground message or getting hit/casted on?

For instance ive been pulling in MM all day and i'll have a melee mob from the gate to the back of the GY and i'll FD, con him and it'll still say ready to attack and they will still come after me.

I've read the wiki on FD and its not really said anything about this going on.

Another example is my attempt to PL my friend in SK, id get the mob to 20% FD and still have aggro, i'd have to FD again to clear it. Is this normal?