I face the same problem. This looks like a stupid IE bug, I wasted hours of time struggling on this issue.

I noticed you can't get or set the onload event for iframe in I.E. When you get, you always get null even you put the onload attribute in the tag. When you set it, you can get what you set, seems it's ok. But the I.E will only call the one you specified in the IFRAME tag. Just ignore what you set. That's strange.
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