function showSelectBox(id)
{
	document.getElementById("coaching").style.display = "none";
	document.getElementById("training").style.display = "none";
	document.getElementById("overig").style.display = "none";
	
	switch(id)
	{
		
		case "coaching":
			document.getElementById(id).style.display = "";
			break;
		
		case "training":
			document.getElementById(id).style.display = "";
			break;
			
		case "overig":
			document.getElementById(id).style.display = "";
			break;
		
		}
}