function checkNull(obj){
		var n = obj.previousSibling;
		while(n.nodeType!=1){
			n = n.previousSibling;
		} 
		str = n.value.replace(/^\s+/g,"");
		if(str.length<1)
		{
			alert('pls add your model details!');
			return false;
		}
		return true;
	}