diff --git a/db/StoredProcedures.sql b/db/StoredProcedures.sql
index b452bdd3e79d2f863401f349e2b0c9ccc209b79c..6918a29732a6d6d75923a9310d04aff78e22e15f 100644
--- a/db/StoredProcedures.sql
+++ b/db/StoredProcedures.sql
@@ -1697,6 +1697,10 @@ CREATE FUNCTION `ChangeDiscipline`	(	`TeacherID` 	INT,
 BEGIN 
     DECLARE checker INT;  					 
 	
+	IF NOT (Grade > 0) THEN
+		RETURN -1;
+	END IF; 
+	
 	SELECT disciplines_teachers.ID
 	INTO checker 
 	FROM `disciplines_teachers`