function formCheck(theForm) {
	var start = theForm.start_year.value;
	var end = theForm.end_year.value;

	if ((theForm.cat5.checked || theForm.cat4.checked || theForm.cat3.checked || theForm.cat2.checked || theForm.cat1.checked || theForm.cat0.checked || theForm.catS.checked || theForm.catE.checked || theForm.catL.checked || theForm.catD.checked) && start<=end) {
		document.getElementById("submitButton").style.display = "none";
		if (navigator.appName == "Microsoft Internet Explorer") {
			document.getElementById("loading").innerHTML = "<img src='images/loading.gif'> Loading...";
		} else {
			document.getElementById("loading_else").style.display = "block";        
		}
		return true;
	} else {
		if(start > end) {
			alert("End Year must be greater than Start Year");
		} else {
			alert("Please select at least one category");
		}
		return false;
	}
}