Problem printing iframe srced to svg content in IE10/11

Having trouble printing an IFrame filled with svg file content. The following works in many other browsers but in IE10/11 I get:
Unhandled exception at line 2417, column 1 in res://ieframe.dll/preview.js (an autogenerated file)
JavaScript runtime error: Unable to get property 'tagName' of undefined or null reference
in var fFrameset = (g_fHasBody && this._aaRect[1][0].contentDocument.body.tagName.toUpperCase() == "FRAMESET");
This same code works well in IE too, if frame content is HTML, not svg:

<script>
functiontestPrint(frmnm) {
varfrm = window.frames[frmnm];
frm.focus();
frm.print();
returnfalse;}
</script>