JS Character Counter

i have a little problem with the follwoing JS, when i count characters for Input type text the reult is ok but when i am using textArea it says 'NAN' here is my code,

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<script language = "Javascript">

function taLimit() {
var taObj=event.srcElement;
if (taObj.value.length==taObj.maxLength*1) return false;
}

function taCount( taObj ) {
var lbObj=document.getElementById("myC");
if (taObj.value.length>(taObj.maxLength*1))
{
taObj.value=taObj.value.substring(0,(taObj.maxLength*1))
};
var count;
count = taObj.maxLength-taObj.value.length;
lbObj.innerHTML=parseInt(count);


}
</script>

<input type="text" name="anyname" size="50" maxlength="50" onkeypress="return taLimit()" onKeyDown="return taCount(this)" ><br><font size=1>Characters Remaining:&nbsp;</font><B><font size=2 color=red><SPAN id=myC>50</SPAN></font></B><br>
<textarea type="text" name="anyname" size="50" maxlength="50" onKeyDown="taCount(this)" ></textarea>