Why the textfield's text doesn't show on the screen?

1

Hello, I have one textfield which is presented like
_root.screen1.screen2.textfield1

screen2 is the movieclip within screen1. They are movieclips and textfield1 is the textfield

I tested like
_root.screen1.screen2.textfield1.text=“Hi, can u see me?”;
trace(_root.screen1.screen2.textfield1.text);

Then I can see the result of trace which have the text I wrote, but I cannot see anything on the screen.

Could any one give some hint for why it is like this and how to modify then ?

Thanks a lot in advance!