diff --git a/impl/src/main/java/de/fitko/fitconnect/impl/SubmissionSender.java b/impl/src/main/java/de/fitko/fitconnect/impl/SubmissionSender.java
index a3953b0b9f512d5b5ef4659ed1f97fcef3e11ccb..a2ff79758b6c14d3470190ea367756a02ac756bd 100644
--- a/impl/src/main/java/de/fitko/fitconnect/impl/SubmissionSender.java
+++ b/impl/src/main/java/de/fitko/fitconnect/impl/SubmissionSender.java
@@ -61,6 +61,7 @@ public class SubmissionSender implements Sender {
         try {
             return Optional.of(authService.authenticate(clientId, clientSecret, scope));
         } catch (AuthenticationException e) {
+            logger.error("client could not be authenticated", e.getMessage());
             return Optional.empty();
         }
     }