diff --git a/app/models/submission.rb b/app/models/submission.rb
--- a/app/models/submission.rb
+++ b/app/models/submission.rb
@@ -34,8 +34,8 @@
 
   def self.find_in_range_by_user_and_problem(user_id, problem_id,since_id,until_id)
     records = Submission.where(problem_id: problem_id,user_id: user_id)
-    records = records.where('id >= ?',since_id) if since_id > 0
-    records = records.where('id <= ?',until_id) if until_id > 0
+    records = records.where('id >= ?',since_id) if since_id and since_id > 0
+    records = records.where('id <= ?',until_id) if until_id and until_id > 0
     records.all
   end