llGetRootPosition?

I'm calling llGetRootPosition() from a child prim in a linked set and getting the position of the child object, not the parent's (i.e, llGetRootPosition() and GetLocalPos() return identical vectors). I'd like to get the parent's position as the llGetRootPosition() documentation suggests. Am I missing something?

I wasn't able to reproduce what you're seeing. The only reason that llGetRootPosition() and llGetLocalPos() could possibly return the same vector is if the script is in the root prim itself, because in that case llGetLocalPos() returns the same as llGetPos().