It is working; your problem can be some bug.
I would recommend implementing such features only on client side in Javascript though, because this even it too frequent. For a code sample, please see my recent answer:
Text Area html Control[
^].
This code is very similar to what you need but makes sense (frankly, your requirement does not make practical sense: you want to copy all text from a text box to a label of every input; why if the user can see the text being typed anyway?).
—SA