diff --git a/components/workflow-core/src/main/java/org/workflow/core/service/app/AbstractAppRequestBuilder.java b/components/workflow-core/src/main/java/org/workflow/core/service/app/AbstractAppRequestBuilder.java
index a7ef1c5da..d43efb708 100644
--- a/components/workflow-core/src/main/java/org/workflow/core/service/app/AbstractAppRequestBuilder.java
+++ b/components/workflow-core/src/main/java/org/workflow/core/service/app/AbstractAppRequestBuilder.java
@@ -128,7 +128,7 @@ protected Callback getHistoricalGraphData(String user, List<Range> months, List<
         Callback returnCall;
 
         for (Range month : months) {
-            taskList = activityClient.getHistoricTasks(month.getStart(), month.getEnd(), getProcessDefinitionKey(), user);
+            taskList = activityClient.getHistoricTasks(month.getStart(), month.getEnd(), getProcessDefinitionKey(), user.toLowerCase());
             data.add(taskList.getTotal());
 
         }
diff --git a/components/workflow-core/src/main/java/org/workflow/core/service/sub/AbstractSubRequestBuilder.java b/components/workflow-core/src/main/java/org/workflow/core/service/sub/AbstractSubRequestBuilder.java
index 0b147a530..836cfa9a8 100644
--- a/components/workflow-core/src/main/java/org/workflow/core/service/sub/AbstractSubRequestBuilder.java
+++ b/components/workflow-core/src/main/java/org/workflow/core/service/sub/AbstractSubRequestBuilder.java
@@ -211,7 +211,7 @@ protected Callback getHistoricalGraphData(String user, List<Range> months, List<
         Callback returnCall;
 
         for (Range month : months) {
-            taskList = activityClient.getHistoricTasks(month.getStart(), month.getEnd(), getProcessDefinitionKey(), user);
+            taskList = activityClient.getHistoricTasks(month.getStart(), month.getEnd(), getProcessDefinitionKey(), user.toLowerCase());
             data.add(taskList.getTotal());
         }