no ";" after while(1)

also the screen position is relative to the top left corner.
and you have to call the panel by the name you defined it with (boxie_pan)
higher Y values are actually in the DOWN direction
so its like this:

function animateboxie()
{
while(!key_d) wait(1);
while(1)
{
if(key_d) boxie_pan.pos_y -= 24 * time_step;
}
}

also make sure animateboxie() is called somewhere, like in main() or in an action.