~Prim Children Gone Bad~

I made an example script to figure out how to move a single child prim to a new location.

default
{
    state_entry()
    {
        llSay(0, "Hello, Avatar!");
    }

    touch_start(integer total_number)
    {
         llSetLinkPrimitiveParams(2,[PRIM_POSITION, <-.1,0,0>]);
         llSleep(1);
          llSetLinkPrimitiveParams(2,[PRIM_POSITION, <.1,0,0>]);
    }
}

After setting the root prim, and the child prim to the perfect starting location (child over top of mother), I click and this is what happens.
The child moves DOWN and to the center of the root prim, THAN moves like the script wants it to. After that it moves how it's suppose to, except it;s not in the original place I put it, and never returns to were it was before the script ran.
Any ideas what went wrong int he script, and how to make it work the way I want it to?

What it seems like you're doing wrong is thinking that the position you specify is relative to the child's current position. If you expect setting the position to <-.1, 0, 0> will move the prim -0.1 meters in total, regardless of its current position, that's where you're messing up. The position you want to set would be a destination position, relative to the root prim at <0, 0, 0>, and along the prim's local axes...

so basically treat it like rezzing a prim, now to break out the calculator, and do some math ^-^