How can i pass variables from one swf to another?

I tried this, but it do not work:

I have two swf files.
1.swf action
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var thisdata = "hello world!";
loadMovieNum("2.swf", 4, "POST");

2.swf action
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_root.createTextField("txtfield", 1, 500, 500, 1000, 1000);
_root.txtfield.text = _root.thisdata

Thank You,
Joni