Getting a SC 422 when creating a transaction.

Hey there,
I'm currently running some tests and usually my create transaction calls work fine. For some reason I get a 422 Error whenever my amount is over 25 cents.
Example request:

{
"referenceID": "766j0p28a25d8",
"corresponding": {
"name": {
"first": "Ultimate",
"last": "Deptor"
}
},
"type": "pull",
"accounts": {
"sourceAccountID": "xxxxxxxxxxxxxxxxx",
"destinationAccountID": "xxxxxxxxxxxxxxxxx"
},
"amount": "2.01"
}