diff --git a/src/main/java/com/labwork1/app/student/model/OrderSession.java b/src/main/java/com/labwork1/app/student/model/OrderSession.java
index 2e2fc8f..3859afa 100644
--- a/src/main/java/com/labwork1/app/student/model/OrderSession.java
+++ b/src/main/java/com/labwork1/app/student/model/OrderSession.java
@@ -7,7 +7,6 @@ import jakarta.persistence.*;
 @Table(name = "order_session")
 public class OrderSession {
     @EmbeddedId
-    @JsonIgnore
     private OrderSessionKey id;
     @ManyToOne
     @MapsId("sessionId")
diff --git a/src/main/java/com/labwork1/app/student/repository/impl/OrderRepositoryImpl.java b/src/main/java/com/labwork1/app/student/repository/impl/OrderRepositoryImpl.java
index 6c666fd..51a1f99 100644
--- a/src/main/java/com/labwork1/app/student/repository/impl/OrderRepositoryImpl.java
+++ b/src/main/java/com/labwork1/app/student/repository/impl/OrderRepositoryImpl.java
@@ -10,6 +10,7 @@ import jakarta.persistence.EntityManager;
 import jakarta.persistence.PersistenceContext;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.context.annotation.Lazy;
+import org.springframework.transaction.annotation.Transactional;
 
 import java.util.Optional;
 
@@ -38,6 +39,7 @@ public class OrderRepositoryImpl implements OrderRepositoryExtension {
     }
 
     @Override
+    @Transactional
     public Optional<Order> addSession(Long id, Long session, Integer count) {
         if (session <= 0 || count <= 0) {
             throw new IllegalArgumentException("addOrder empty fields");
@@ -54,19 +56,21 @@ public class OrderRepositoryImpl implements OrderRepositoryExtension {
 
         if (currentSession.getCapacity() < count ||
                 (orderSession != null && orderSession.getCount() + count > currentSession.getMaxCount())) {
-            throw new IllegalArgumentException("No more tickets in session. Capacity - "+currentSession.getCapacity()+". Count - "+count);
+            throw new IllegalArgumentException(String.format("No more tickets in session. Capacity: %1$s. Count: %2$s",
+                    currentSession.getCapacity(), count));
         }
         if (orderSession == null)
             orderSession = new OrderSession(currentOrder, currentSession, count);
-        else if (orderSession.getCount() + count <= currentSession.getCapacity())
+        else if (orderSession.getCount() + count <= currentSession.getMaxCount()) {
             orderSession.setCount(orderSession.getCount() + count);
+        }
 
         currentOrder.addSession(orderSession);
         currentSession.addOrder(orderSession);
         currentSession.setCapacity(currentSession.getCapacity() - count);
-        em.merge(orderSession);
         em.merge(currentSession);
         em.merge(currentOrder);
+        em.merge(orderSession);
         return orderRepository.findById(id);
     }