Im trying to PUT a Kit assembly from the API in my test environment. It was working and as I continued to test I noticed that I started getting error relating the PostPeriod?

PUT : 

{

    "AutoBuiltKit": {

        "value": true

    },

    "ReferenceNbr": {

        "value": "<new>"

    },

    "Date": {

        "value": "2023-04-25T00:00:00"

    },

    "Description": {

        "value": "TESTING SO006541"

    },

    "Hold": {

        "value": false

    },

    "KitInventoryID": {

        "value": "ELECOMP2  "

    },

    "Qty": {

        "value": 3

    },

    "PostPeriod": {

         "value": "08-2021"

    },

    "Revision": {

        "value": 10

    },

    "Type": {

        "value": "Balanced"

    },

    "UOM": {

        "value": "EA"

    },

    "WarehouseID": {

        "value": "WHOLESALE "

    }

}

errors below: