Functions should be changed to:

<Script Language="javascript">
    function callInsertImage(Editor_ClientID, daimage)  
    {  
            var editor1 = document.getElementById(Editor_ClientID);
            editor1.FocusDocument();  
            var editdoc = editor1.GetDocument();  
            editor1.ExecCommand('new');
            editor1.ExecCommand('ImageGalleryByBrowsing');
            InputURL(daimage);
            document.getElementById(daimage).focus();
    }    
    
    function InputURL(Editor_ClientID, daimage)
    {
        var editor1 = document.getElementById(Editor_ClientID);
        var editdoc = editor1.GetDocument();  
        var imgs = editdoc.getElementsByTagName("img");
        if(imgs.length>0)  
        {    document.getElementById(daimage).value = imgs[imgs.length-1].src;
        }  
        else
        {
            setTimeout(InputURL,500);
        }  
    }       
</script>