Invalid trade volume error but strategy tester works?

[Ong Kai Wen Kelvin]

Why is it i failed the validation for OrderSend due to invalid trade volume but i am able to send orders in the strategy tester?

[Yashar Seyyedin]

Check this.

Invalid volumes in trade operations

Before sending trade orders, it is also necessary to check the correctness of the volumes specified in the orders. The number of lots that the EA is about to set in the order, must be checked before calling the OrderSend() function. The minimum and maximum allowed trading volumes for the symbols are specified in the Specification, as well as the volume step. In MQL5, these values can be obtained from the ENUM_SYMBOL_INFO_DOUBLE enumeration with the help of the SymbolInfoDouble() function.

SYMBOL_VOLUME_MIN	Minimal volume for a deal
SYMBOL_VOLUME_MAX	Maximal volume for a deal
SYMBOL_VOLUME_STEP	Minimal volume change step for deal execution

Example of function for checking the correctness of the volume

//+------------------------------------------------------------------+
//| Check the correctness of the order volume                        |
//+------------------------------------------------------------------+
bool CheckVolumeValue(double volume,string &description)
  {
//--- minimal allowed volume for trade operations
   double min_volume=SymbolInfoDouble(Symbol(),SYMBOL_VOLUME_MIN);
   if(volume<min_volume)
     {
      description=StringFormat("Volume is less than the minimal allowed SYMBOL_VOLUME_MIN=%.2f",min_volume);
      return(false);
     }

//--- maximal allowed volume of trade operations
   double max_volume=SymbolInfoDouble(Symbol(),SYMBOL_VOLUME_MAX);
   if(volume>max_volume)
     {
      description=StringFormat("Volume is greater than the maximal allowed SYMBOL_VOLUME_MAX=%.2f",max_volume);
      return(false);
     }

//--- get minimal step of volume changing
   double volume_step=SymbolInfoDouble(Symbol(),SYMBOL_VOLUME_STEP);

   int ratio=(int)MathRound(volume/volume_step);
   if(MathAbs(ratio*volume_step-volume)>0.0000001)
     {
      description=StringFormat("Volume is not a multiple of the minimal step SYMBOL_VOLUME_STEP=%.2f, the closest correct volume is %.2f",
                               volume_step,ratio*volume_step);
      return(false);
     }
   description="Correct volume value";
   return(true);
  }