JS: Iframe problem

[akswithsim]

I am using iframe structure as shown below
Main Window
----IFrame 1 (inside main window)
--------Iframe 2 (inside Iframe1)
----------------Iframe 3 (inside Iframe2)

From Iframe2, to call Iframe3 I am using following code
---------------
var obj = window.frames["Iframe3"];
---------------
Above code is throwing error as shown below
In IE 6 - Permission Denied.
In IE 7 - Object Expected.
In Firefox - Working fine.

One more infomation :
I am using Iframe SRC of same domain. (not external link is there).

Can anybody help me. Its urgent?
Thanks in advance

[Costin Trifan]

instead of using var obj = window.frames["Iframe3"];
try this: var obj = document.getElementById("Iframe3");

[akswithsim]

thanks costin_trifan for replay. problem solved, just by reloading the window. But don't know why it is happening?

[Costin Trifan]

Maybe it's just an IE bug...

[akswithsim]

May be, but problem was in IE 6 and IE 7 both. It means IE 7 still have some bugs.

[Costin Trifan]

All browsers have a problem or more...

(Why IE should be different?)

[Arenlor]

The major bug I see in IE is it has it's own tags and the like. That and it's made by Microsoft.