Injecting Javascript Not Working

Because of the way we are loading these pages, we want to use the DOM to inject <SCRIPT> variables and source...

function putJS(cid, pid) {
    var _line1 = '<scr' + 'ipt>var zflag_nid="607"; var zflag_cid="' + cid + '"; var zflag_sid="' + pid + '"; var zflag_width="1"; var zflag_height="1"; var zflag_sz="94";<\/script>';
    var _line2 = "<scr" + "ipt src='http://newt1.com/jsc/z5/fo.js'><\/script>";
    var _script = document.createElement("div");
    _script.innerHTML = _line1 + _line2;
    (document.getElementsByTagName("body")[0] || document.documentElement).appendChild(_script);
}

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But, for some reason - its not working.

I've also tried:

function putJS(cid, pid) {
   var _script = document.createElement("script");
    _script.innerHTML = 'var zflag_nid="607"; var zflag_cid="' + cid + '"; var zflag_sid="' + pid + '"; var zflag_width="1"; var zflag_height="1"; var zflag_sz="94";';
    //_script.onload = scriptLoaded;
    var _scriptSource = document.createElement("script");
    _scriptSource.src = "http://www.com/fo.js";
    _script.async = true;
    _scriptSource.async = true;
    var docFrag = document.createDocumentFragment();
    docFrag.appendChild(_script);
    docFrag.appendChild(_scriptSource);
    (document.getElementsByTagName("head")[0] || document.documentElement).appendChild(docFrag);
}

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And I get an error about writing to the page...  

I'm not sure if there is anything I can do... I have no access to the fo.js script also, as its being loaded externally from a source we do not own.

Thanks