diff --git a/stat/pool.go b/stat/pool.go
index 58b4ebfc..13f460e4 100644
--- a/stat/pool.go
+++ b/stat/pool.go
@@ -2,6 +2,7 @@ package stat
 
 import (
 	"encoding/hex"
+	"fmt"
 	"sync"
 	"time"
 )
@@ -26,10 +27,12 @@ func NewPoolStatistic() *PoolStat {
 func (s *PoolStat) OperationCallback(nodeKey []byte, endpoint string, method Method, duration time.Duration, err error) {
 	if len(nodeKey) == 0 {
 		// situation when we initialize the client connection and make first EndpointInfo call.
+		fmt.Println("1111")
 		return
 	}
 
 	if !IsMethodValid(method) {
+		fmt.Println("2222")
 		return
 	}
 
@@ -55,10 +58,12 @@ func (s *PoolStat) OperationCallback(nodeKey []byte, endpoint string, method Met
 	s.mu.Unlock()
 
 	if duration > 0 {
+		fmt.Println("3333")
 		mon.methods[method].incRequests(duration)
 	}
 
 	if err != nil {
+		fmt.Println("4444")
 		mon.incErrorRate()
 	}
 }