llListFindList problem

I have a list of the names of prims:
list prims = ["SW","","SE","","NE","","NW",""];
in a script that listen for messages from other prims.

The prims send a message with their position. For example the prim named SW does

llSay(channel,(string)llGetPos());

In the main script there is:

listen(integer channel, string name, key id, string msg){
if(llListFindList(prims,[name]) != -1){
integer I = llListFindList(prims,[name]);
prims = llListReplaceList(prims,[(vector)mgs], I + 1, I +1)
}
}

Can you tell me why this if statement does not get triggered.. I have put in a llOwnerSay(name) before the if statement and so I know the message gets there.

You're sure the names of the prims sending the chats are EXACTLY the same as the names you have in the list? No upper/lower case differences, spaces, etc.?

Only thing I can think is something higher up in the script..does the llListen statement call the same channel?