backtest, not position open, oil

[valenciaorange]

I am backtesting.

I was able to create a position in the dollar yen.

However, I couldn't create a position with oil.

Why does this phenomenon occur?

  static int count = 0;

   double ask = SymbolInfoDouble(NULL, SYMBOL_ASK);

   string symbol = Symbol();

   if(count < 10 &&

      ticket == 0)

     {

      ticket = trade.PositionOpen(symbol, ORDER_TYPE_BUY, 1, ask, ask-1, 0);

      //ticket = trade.Buy(1,symbol,ask,0,0);

      Print("err=",GetLastError());

      count++;

     }