实际交易数量与exchange.Buy设置的数量不符。

下面是我用的测试大吗，非常简单，每个小时以市价购入10个ETH，初试价格是10000，但是在模拟回测的时候发现每次都显示交易成功，但是交易的量都不是10.

function onTick() {
    var id = exchange.Buy(-1, 10);
    Log("Order Id:", id);
    Log(exchange.GetOrder(id));
    Log(exchange.GetTrades());
    Log(exchange.GetAccount());
}

function main() {
    Log(exchange.GetAccount());
    while (true) {
        onTick();
        Sleep(3600 * 1000);
    }
}

この取引のログは

2018-03-05 06:00:25		信息	{"Balance":9699.61809,"Stocks":0.33250049999999987,"FrozenBalance":0,"FrozenStocks":0}
2018-03-05 06:00:24		信息	[{"Id":31,"Time":1520200824800,"Price":900,"Amount":1,"Type":1}]
2018-03-05 06:00:24		信息	{"Id":31,"Price":-1,"Amount":10,"DealAmount":10,"Type":0,"Status":1,"AvgPrice":900.01}
2018-03-05 06:00:24		信息	Order Id: 31
2018-03-05 06:00:24	OKCoin_EN	买入	市价	10

理由はご存知ですか?