Ciao a tutti!
Ho una funzione JavaScript:
coloraCella : function() { alert("siii"); },
richiamata da "initialize" in questo modo:
this.coloraCella();

ma firebug mi segnala: IS NOT A FUNCTION

come mai? come posso rosolvere?

codice:
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
	<title>Tabella</title>
	<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
	<link rel="stylesheet" type="text/css" href="CSS/screen.css" />
	<script type="text/javascript" src="./js/prototype.js"></script>

	<script type="text/javascript">
	
	var EditTable = Class.create();

	EditTable.prototype = {

		t : null,
		td : null,
		tr : null,
		nameClass : null,
		parametersClass : null,

    	initialize: function () {			
    		
    			$$('table')[0].observe( 'click', function (event) { 
    					var elt = Event.element(event);
        				if( elt.nodeName == "TD" ) {
        					this.td = elt;
        					//alert("td = " +  this.td);
        					
        					this.tr = this.td.up('tr');
        					//alert("tr = " +  this.tr);
							
        					this.t = this.td.up('table');
        					//alert("t = " +  this.t);
        	
        					
        					this.nameClass = this.t.down().textContent;
        					//alert("nameCLass = " +  this.nameClass);

							//prelevo i parametri
        					var elt_thead = this.t.down('thead');
        					elt_thead = elt_thead.down('tr');
        					var par = new Array();  					
        					elt_thead.descendants().each(function(s, index) {
            					par[index] = s.textContent;
            					//alert("element : " + par[index]);
        					});
            				this.parametersClass = par;
            				//alert(this.parametersClass);

							
            				this.coloraCella();
            				
        				} //if TD
    			}); //observe table
    			
			}, //initialize
		
		coloraCella : function() {
				alert("siiii");	
			}
	};

	
	var Table = function () {
		var t = new EditTable;
	}
	
	document.observe("dom:loaded", Table);
	
	</script>


	
</head>
<body>


    <table>
    		<caption>
    		CAPTION
    		</caption>
            <tfoot>
                        <tr>
                                 <td>aaaaaa</td>
                        </tr>
            </tfoot>
            <thead>
            		<tr>
            			<th>
            			PARAMETRO_1
            			</th>
            			<th>
            			PARAMETRO_2
            			</th>
            		</tr>
            </thead>
            <tbody>
                        <tr>
                                <td>primo</td>
                                <td>uno</td>
                        </tr>
                         
                        <tr>
                                <td>secondo</td>
                                <td>due</td>
                        </tr>
                        
                        <tr>
                                <td>terzo</td>
                                <td>tre</td>
                        </tr>
                        <tr>
                                <td>quarto</td>
                                <td>quattro</td>
                        </tr>
            </tbody>
    </table>
    
</body>
</html>
Grazie!