diff --git a/extensions/chart/src/chartLayout.vue b/extensions/chart/src/chartLayout.vue
index 28d3d76..461949e 100644
--- a/extensions/chart/src/chartLayout.vue
+++ b/extensions/chart/src/chartLayout.vue
@@ -152,7 +152,7 @@ watchEffect(() => {
 
   data.value.datasets.forEach((dataset) => {
     dataset.data.forEach((dataUnit, index) => {
-      if (!DataUtil.indexNumber(dataUnit) && data.value.labels && (data.value.labels[index] as DateTime).isValid) {
+      if (!dataUnit.index && data.value.labels && (data.value.labels[index] as DateTime).isValid) {
         dataUnit.index = data.value.labels[index] as DateTime
       }
     })
diff --git a/test/src/App.vue b/test/src/App.vue
index a1e6732..ec11880 100644
--- a/test/src/App.vue
+++ b/test/src/App.vue
@@ -44,19 +44,17 @@ onMounted(() => {
       )"
     >
       <ChartDataset label="test1" :style="{ borderColor: '#f00', backgroundColor: '#f00' }">
-        <ChartData
-          :cross="1"
-          :style="{ borderRadius: 8 }"
-        />
-        <ChartData :cross="1" />
         <ChartData :cross="1" />
+        <ChartData :cross="2" />
+        <ChartData :cross="0" />
         <ChartData :cross="1" />
       </ChartDataset>
-      <ChartDataset label="test2" :style="{ borderColor: '#ff0', backgroundColor: '#ff0', borderRadius: 4 }">
+      <ChartDataset label="test2" :style="{ borderColor: '#ff0', backgroundColor: '#ff0', borderRadius: 4, tension: 0.2 }">
         <ChartData :cross="2" />
         <ChartData :cross="1" />
         <ChartData :cross="3" />
         <ChartData :cross="2" />
+        <ChartData :cross="1.5" :index="DateTime.fromISO('2021-03-15').setLocale('en-US')" />
       </ChartDataset>
     </LineChart>
   </Motion>