Not support market order error

I've been asked what causes the following frequently suggested errors:

2017-02-07 17:30:14 BotVS error Sell: Not support market order 2017-02-07 17:30:13 BotVS error Buy: Not support market order

It's a simple call. exchange.Buy (((1); exchange.Sell (((1);

Is the inventor able to quantify the price when the analog platform is running?