[wMan]

got error on global,js error making line

        obj.firstChild.nodeValue = val;

part of code

function descriptor(val) {
        var obj;
        obj = document.getElementById("descriptor");
        if (!obj) return;
        obj.firstChild.nodeValue = val;
}

error code Error: obj.firstChild is null
Source File: http://pegasus.woano.lv/global.js
Line: 54

i bet i screwed up something