cannot found the custom metrics

I use this

aws rum batch-create-rum-metric-definitions --app-monitor-name GlobalStoreMobileShoppingWebapp --destination CloudWatch --destination-arn arn:aws:iam:: --metric-definitions '[{"Name": "buttonMetric","Namespace": "myService","ValueKey": "event_details.visit_count","UnitLabel": "Count","DimensionKeys": {"event_details.buttonName": "buttonName"},"EventPattern":"{\"event_type\":[\"my_custom_event\"],\"event_details\": {\"buttonName\": [\"buttonName\"]}}"}]' --debug

and when i do

aws rum batch-get-rum-metric-definitions --app-monitor-name GlobalStoreMobileShoppingWebapp --destination CloudWatch --destination-arn arn:aws:iam::

it do list the result

{
"MetricDefinitions": [
{
"DimensionKeys": {
"event_details.buttonName": "buttonName"
},
"EventPattern": "{\"event_type\":[\"my_custom_event\"],\"event_details\": {\"buttonName\": [\"buttonName\"]}}",
"MetricDefinitionId": "",
"Name": "buttonMetric",
"Namespace": "myService",
"UnitLabel": "Count",
"ValueKey": "event_details.visit_count"
}
]
}

but cannot found the custom metrics on cloud watch Metrics.

Thank you for you help.