bigblue button join API generating link not working

Question

Post: localhost:3000/bx_block_classes/meetings/join

Body:

 {
 "meeting_id": "class-4-gg-135",#generated by create API
 "first_name": "Student", 
 "last_name": "demo",
 "password":"yENfzgxG"
 }

Response:

{
    "join_link": "https://test-install.blindsidenetworks.com/bigbluebutton/api/join?fullName=Studentdemo&meetingID=class-4-gg-135&password=yENfzgxG&checksum=3c2cdf84a2fd2ed521c6a8a6848c22a0f77f3579",
    "is_meeting_running": false
}

The join_link generated not working , showing meeting id does not exist.