Help Me Follow Problem

[kyawthiha-mmds]

Help Me
How to solve follow problem
Messenger Event
After User send image ,context.event.isImage is always false
console.log (context.event.rawEvent)
after User send image
{
"sender": {
"id": "4494677857271549"
},
"recipient": {
"id": "103015448261301"
},
"timestamp": 1605992706687,
"message": {
"mid": "m_KKmmQZN0LPxmrh-_OTA7BFkfzS4S352mm1pzYWbI_n6WNvLI7UeVmsCDHwL37y1pqgRRoORKvk7pXtv8r9ST9A"
}
}