it's usefull for real live trading when trade is busy:

extern int NumberOfTries = 10;
...
when open trade
for(c=0;c<NumberOfTries;c++)
ticket=OrderSend(Symbol(),OP_BUY,...)
err=GetLastError();
if(err==0)
{
if(ticket>0) break;
}
else
{if(err==0 || err==4 || err==136 || err==137 || err==138 || err==146) //Busy errors
{
Sleep(5000);
continue;
}
else //normal error
{
if(ticket>0) break;
}