Не работает функция копинаме

<script type="text/javascript">   
    function  copyfileName() {
        var name;
        var file = document.upload.elements["file[]"];
        var file_name = document.upload.elements["fileName[]"];
        var alt = document.upload.elements["alt[]"];
        if (file.length > 0){
            for (i = 0; (i < file.length); i++) {
                if (file_name[i].value != file[i].value){
                    file_name[i].value = file[i].value;
                    name = file_name[i].value.slice(file_name[i].value.lastIndexOf("\\")+1,file_name[i].value.lastIndexOf('.'));
                    alt[i].value = name.replace(/_|-/g," ");
                }
            }
        }else{
            file_name.value = file.value;
            name = file_name.value.slice(file_name.value.lastIndexOf("\\")+1,file_name.value.lastIndexOf('.'));
            alt.value = name.replace(/_|-/g," ");
        }
    }
</script> 
<table>
<input type="text" id="fileName" name="fileName[]"   readonly="readonly" />
<input type="file" name="file[]" id="file"  onchange="javascript: copyfileName()" /><br>
<textarea type="text" name="alt[]" onclick=setFieldName(this.name) id="short_story" style="width:650px; border-radius: 0px 0px 3px  3px;"  rows="7">{short-story}</textarea>    
</table>