Variable clip names

1

All I want to do is use the students choice to control a clip name variable which moves the clip according to that variable, but it won’t work. What could be the problem?

choiceA is the name of a component combo box. When I trace clip_var it shows the correct choice, like clip1 or clip4. But it won’t move the clip and when I trace clip_var._y it shows undefined.

k = choiceA.selectedIndex;
var clip_var = “clip”+k;
trace(clip_var);
clip_var._y = 5;
trace(clip_var._y);