Why aren't my custom carrier service rates loading at checkout?

We are having trouble getting shopify to receive rates from our custom carrier service app. Whenever a customer tries to checkout from our store the shipping methods will not load properly and we get this error message.

this is my POST end point

https://script.google.com/macros/s/AKfycbyJTUkgZjJWWCWiREbEd-vgB33MYItrUv7gCB7iSZa0W2ltOKXiD0j52Y6l38TQS5Fp-w/exec

your answer is static for testing purposes the same as in the documentation

{
“rates”: [
{
“service_name”: “Quenty”,
“service_code”: “ON”,
“total_price”: “1295”,
“description”: “This is the fastest option by far”,
“currency”: “CAD”,
“min_delivery_date”: “2013-04-12 14:48:45 -0400”,
“max_delivery_date”: “2013-04-12 14:48:45 -0400”
},
{
“service_name”: “Quenty2”,
“service_code”: “2D”,
“total_price”: “2934”,
“currency”: “USD”,
“min_delivery_date”: “2013-04-12 14:48:45 -0400”,
“max_delivery_date”: “2013-04-12 14:48:45 -0400”
},
{
“service_name”: “Quenty3”,
“service_code”: “1D”,
“total_price”: “3587”,
“currency”: “USD”,
“min_delivery_date”: “2013-04-12 14:48:45 -0400”,
“max_delivery_date”: “2013-04-12 14:48:45 -0400”
}
]
}