XRP Test Net Payment Transactions

[thundercraker]

Hello all,

I've been trying to make some manual JSON RPC based payments from one of my test wallets to another in the XRP test net. However, each attempt has resulted in:

{
  "error": "amendmentBlocked",
  "error_code": 14,
  "error_message": "Amendment blocked, need upgrade.",
}

The server in question is https://api.altnet.rippletest.net:51234/

The call that I used was essential simply a copy paste from https://ripple.com/build/rippled-apis/#submit, with the address and secret set to my own.

{
    "method": "submit",
    "params": [
        {
            "offline": false,
            "secret": "s████████████████████████████",
            "tx_json": {
                "Account": "rf1BiGeXwwQoi8Z2ueFYTEXSwuJYfV2Jpn",
                "Amount": {
                    "currency": "USD",
                    "issuer": "rf1BiGeXwwQoi8Z2ueFYTEXSwuJYfV2Jpn",
                    "value": "1"
                },
                "Destination": "ra5nK24KXen9AHvsdFTKHSANinZseWnPcX",
                "TransactionType": "Payment"
            },
            "fee_mult_max": 1000
        }
    ]
}

From my understanding of the various errors, "AmendmentBlocked" reflects that the node is somehow incapable of handling the request, possibly due to the version being too old. But then again, is this not the official test net? How could it be behind?