type: "check_box" Return value undefined

Hi,

I coded a Javacript window with different items that fill in elements of form that is used as a stamp. Textboxes and radio buttons are working fine, however I'm struggling with retrieving the Check box informatio: Console says undefined. Here is the relevant piece of code:

// Dialog Definition 
var oDlg = 
	{
	strchkPaid: "False",
	
	initialize: function(dialog) 
		{ 
	    dialog.load
			(
			{
			"chkPaid":this.strchkPaid,
			}
			); 
		},
        commit: function(dialog) 
		{ 
            var data = dialog.store();
			this.strchkPaid= data["chkPaid"];
		},
        description:
		{ 
			name: "Refacturation",
			elements: 
			[
				{ 
				type: "view",
				elements: [
					{
						item_id: "chkPaid",
						name: "Payé par carte de crédit",
						type: "check_box",
					},	
				] 
				},
			] 
		}
};

// Dialog Activation 
app.execDialog(oDlg)
if((event.source.forReal)&&(event.source.stampName == "#EtampeTI"))
{
if(oDlg.strchkPaid){this.getField("chkBoxPaid").value = "Yes";}else{this.getField("chkBoxPaid").value = "No";}
}

oDlg.strchkPaid seems to return undefined.

Any ideas?

Thanks in advance.