function validateForm(strForm) {
	var bError = false;
	for (var iField = 1; iField <= 20; iField++)
	{
		//alert("iField="+document.getElementById("field_"+iField))
		
		if (document.getElementById("field_"+iField)) {
			var strInhoud = document.getElementById("field_"+iField).value;
			var strchecked = document.getElementById("field_"+iField).checked;
			
			//alert("strInhoud="+strInhoud+" index="+strInhoud.indexOf("radio"))
			
			if (strInhoud.indexOf("radio")>=0) {
				
				var radio = document.getElementsByName(strInhoud.substr(6))
				var bRadioButtonchecked = false;
				for (var iRadioIndex = 0; iRadioIndex < radio.length; iRadioIndex++)
				{
					if (radio[iRadioIndex].checked) {						
						bRadioButtonchecked = true;
					}
				}				
				if (bRadioButtonchecked == false) {
					document.getElementById("required_"+iField).style.display = "inline";
					bError = true; 					
				}		
				else {
					document.getElementById("required_"+iField).style.display = "none";
				}
			}
			else if ((strInhoud == '') || (strInhoud =='Maak een keuze') || (strInhoud =="on" && !strchecked)) {
				document.getElementById("required_"+iField).style.display = "inline";
				bError = true; 
			}
			else {
				document.getElementById("required_"+iField).style.display = "none";
			}
		}		
	}
	
	if (bError) {
		document.getElementById("reqForm").style.display = "inline";
	}	
	else {
		document.getElementById(strForm).submit();
	}
}