Hi, recently I started getting error 4756 messages saying that my buy or sell order could not be placed. Is there something wrong with my code?

   if(Sell_Condition_1 && Sell_Condition_2 && Sell_Condition_3 && Sell_Condition_4 && Sell_Condition_5 && Sell_Condition_6 && Sell_Condition_7)
        {
         // any opened Sell position?
         if(Sell_opened || Buy_opened)
           {
            Alert("We already have a Sell position!!!");
            return;    // Don't open a new Sell Position
           }
         ZeroMemory(mrequest);
         ZeroMemory(mresult);
         mrequest.action=TRADE_ACTION_DEAL;                                // immediate order execution
         mrequest.price = NormalizeDouble(latest_price.bid,_Digits);           // latest Bid price
         mrequest.symbol = _Symbol;                                          // currency pair
         mrequest.volume = 0.5;                                              // number of lots to trade
         mrequest.magic = EA_Magic;                                          // Order Magic Number
         mrequest.type= ORDER_TYPE_SELL;                                     // Sell Order
         mrequest.type_filling = ORDER_FILLING_FOK;                          // Order execution type
         mrequest.deviation=100;                                             // Deviation from current price
         mrequest.sl = NormalizeDouble(latest_price.bid + STP*_Point,_Digits);
         mrequest.tp = NormalizeDouble(latest_price.bid - latest_price.bid,_Digits);
         //--- send order
         OrderSend(mrequest,mresult);
         // get the result code
         if(mresult.retcode==10009 || mresult.retcode==10008) //Request is completed or order placed
           {
            Alert("A Sell order has been successfully placed with Ticket#:",mresult.order,"!!");
           }
         else
           {
            Alert("The Sell order request could not be completed -error:",GetLastError());
            ResetLastError();
            return;
           }
        }

   if(Buy_Condition_1 && Buy_Condition_2 && Buy_Condition_3 && Buy_Condition_4 && Buy_Condition_5 && Buy_Condition_6 && Buy_Condition_7)
        {
         // any opened Buy position?
         if(Buy_opened || Sell_opened)
           {
            Alert("We already have a Buy Position!!!");
            return;    // Don't open a new Buy Position
           }
         ZeroMemory(mrequest);
         ZeroMemory(mresult);
         mrequest.action = TRADE_ACTION_DEAL;                                  // immediate order execution
         mrequest.price = NormalizeDouble(latest_price.ask,_Digits);           // latest ask price
         mrequest.sl = NormalizeDouble(latest_price.ask - STP*_Point,_Digits); // Stop Loss
         mrequest.tp = NormalizeDouble(latest_price.ask + TKP*_Point,_Digits); // Take Profit
         mrequest.symbol = _Symbol;                                            // currency pair
         mrequest.volume = 0.5;                                                 // number of lots to trade
         mrequest.magic = EA_Magic;                                             // Order Magic Number
         mrequest.type = ORDER_TYPE_BUY;                                        // Buy Order
         mrequest.type_filling = ORDER_FILLING_FOK;                             // Order execution type
         mrequest.deviation=100;                                                // Deviation from current price
         //--- send order
         OrderSend(mrequest,mresult);
         // get the result code
         if(mresult.retcode==10009 || mresult.retcode==10008) //Request is completed or order placed
           {
            Alert("A Buy order has been successfully placed with Ticket#:",mresult.order,"!!");
           }
         else
           {
            Alert("The Buy order request could not be completed -error:",GetLastError());
            ResetLastError();           
            return;
           }
        }