Trading is not offered for this duration.

I'm trying to create a trading application but the problem is when I request a proposal so I can buy a contract, I get the weirdest of errors.
I've tried different Symbols to trade on but all, except for the R_XX ones come back with a similar exception. Currently I am using a virtual account, not sure if that is what is causing the problem because I can do similar trades on the smart trader on the website.
Here's are some of the JSON requests
{ "proposal": 1, "amount": "10", "basis": "stake", "contract_type": "CALL", "currency": "USD", "duration": "5", "duration_unit": "m", "barrier": "+0.00", "symbol": "frxAUDJPY" }

{ "proposal": 1, "amount": "10", "basis": "stake", "contract_type": "PUT", "currency": "USD", "duration": "5", "duration_unit": "m", "barrier": "+0.00", "symbol": "frxXAUUSD" }

And here is the typical response I get:
{"echo_req":{"amount":"10","barrier":"+0.00","basis":"stake","contract_type":"PUT","currency":"USD","duration":"3","duration_unit":"t","product_type":"basic","proposal":1,"symbol":"frxXAUUSD"},"error":{"code":"OfferingsValidationError","message":"Trading is not offered for this duration."},"msg_type":"proposal"}