Unable to Create Zoho Booking via the Book Appointment API

Unable to Create Zoho Booking via the Book Appointment API

Its giving the below error

{
    "response": {
        "errormessage""Error setting value for the variable:customer_details\n null",
        "status""Error"
    }
}


Request: POST

attached Zoho-oauthtoken to header as well

Body/Payload

{
"service_id"112179000000018063,
"staff_id"112179000000018015,
"from_time""30-Apr-2012 05:00:00 PM",
"customer_details": {
"name":"John",
"email":"john1@gmail.com",
"phone_number":"+919876543736"
}
}


Am I doing something wrong here? What is the issue here?