I am attempting to use a PHP RPC Wrapper to connect to bitcoind for RPC API calls, estimatesmartfee, more specifically.

My question is, do I need to specify the argument keys, or just the values?

For example, the below is with just the values

public function getSmartFeeEstimate($blocks)
{
    $command = new \Nbobtc\Command\Command('estimatesmartfee', [$blocks, 'CONSERVATIVE']);
    $response = $this->client->sendCommand($command);
    $contents = $response->getBody()->getContents();

    return $contents;
}

or do I need to specify the keys as well, for example...

public function getSmartFeeEstimate($blocks)
{
    $command = new \Nbobtc\Command\Command('estimatesmartfee', ['conf_target' => $blocks, 'estimate_mode' => 'CONSERVATIVE']);
    $response = $this->client->sendCommand($command);
    $contents = $response->getBody()->getContents();

    return $contents;
}

Normally I would just try each one and see what the functions return, however, I am in regtest mode, and its returning the same thing for both, which leads me to believe that it's ignoring the arguments and just telling me its not working...

{"result":{"errors":["Insufficient data or no feerate found"],"blocks":2},"error":null,"id":null}