How to print IFrame in asp.net

 
Hi,
I want to print iframe content using javascript but getting blank printout. my code is as below. i tried IE and Chrome both.
var fwin;
fwin = self.frames[0]; // or:
fwin = self.frames["myFrame"];
and i also tried
var iframeEl = document.getElementById("myFrame");
var fwin = iframeEl.contentWindow;  
 If someone knows solution, please reply.
Thanks in advance
Regards,
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