minor changes in packing slip
diff --git a/erpnext/stock/doctype/packing_slip/packing_slip.js b/erpnext/stock/doctype/packing_slip/packing_slip.js
index ff02e84..6769845 100644
--- a/erpnext/stock/doctype/packing_slip/packing_slip.js
+++ b/erpnext/stock/doctype/packing_slip/packing_slip.js
@@ -8,12 +8,15 @@
 }
 
 
-cur_frm.fields_dict['items'].grid.get_field('item_code').get_query =
-		function(doc, cdt, cdn) {
-			return {
-				query: "erpnext.stock.doctype.packing_slip.packing_slip.item_details",
-				filters:{ 'delivery_note': doc.delivery_note}
-			}
+cur_frm.fields_dict['items'].grid.get_field('item_code').get_query = function(doc, cdt, cdn) {
+	if(!doc.delivery_note) {
+		frappe.throw(__("Please Delivery Note first"))
+	} else {
+		return {
+			query: "erpnext.stock.doctype.packing_slip.packing_slip.item_details",
+			filters:{ 'delivery_note': doc.delivery_note}
+		}
+	}
 }
 
 cur_frm.cscript.onload_post_render = function(doc, cdt, cdn) {