diff --git a/LearnsMate/src/main/java/intbyte4/learnsmate/lecture/service/LectureFacade.java b/LearnsMate/src/main/java/intbyte4/learnsmate/lecture/service/LectureFacade.java
index e8aa1ca3..3c997ac5 100644
--- a/LearnsMate/src/main/java/intbyte4/learnsmate/lecture/service/LectureFacade.java
+++ b/LearnsMate/src/main/java/intbyte4/learnsmate/lecture/service/LectureFacade.java
@@ -276,14 +276,19 @@ public ResponseFindLectureDetailVO getLectureDetailsWithConversionRates(String l
                 .build();
     }
 
-    private double calculateConversionRate(int clickCount, int purchaseCount) {
-        if (clickCount == 0) {
+    private double calculateConversionRate(Integer clickCount, Integer purchaseCount) {
+        if (clickCount == null || clickCount == 0 || purchaseCount == null) {
             return 0.0;
         }
         return (double) purchaseCount / clickCount * 100;
     }
 
     public LectureStatsVO getLectureStatsWithFilterAndRates(String lectureCode, LectureStatsFilterDTO filter) {
+        log.info(filter.getEndMonth().toString());
+        log.info(filter.getEndYear().toString());
+        log.info(filter.getStartMonth().toString());
+        log.info(filter.getStartYear().toString());
+
         LectureDTO lectureDTO = lectureService.getLectureById(lectureCode);
         if (lectureDTO == null) throw new CommonException(StatusEnum.LECTURE_NOT_FOUND);