fix: Default cost center fix for delivery note item (#17990)

diff --git a/erpnext/selling/doctype/sales_order/sales_order.py b/erpnext/selling/doctype/sales_order/sales_order.py
index fb7a335..b87ad03 100755
--- a/erpnext/selling/doctype/sales_order/sales_order.py
+++ b/erpnext/selling/doctype/sales_order/sales_order.py
@@ -581,8 +581,8 @@
 
 		if item:
 			target.cost_center = frappe.db.get_value("Project", source_parent.project, "cost_center") \
-				or item.get("selling_cost_center") \
-				or item_group.get("selling_cost_center")
+				or item.get("buying_cost_center") \
+				or item_group.get("buying_cost_center")
 
 	target_doc = get_mapped_doc("Sales Order", source_name, {
 		"Sales Order": {