I made an EA, there is a big difference between Demo and Live trade

When I back test this EA by tester for the current 3 years, It runs Ok with almost no errors(except modify error 1).

But when I attached it on living trade, no order can be traded, and the information about error are as below, and I don;t know why trade is disabled?

OrderSend(Symbol(),OP_BUY,Lots,Ask,Slip*Pips_Slip,Stop_Loss,TP,0,Magic_Number,0,0);
OrderSend(Symbol(),OP_SELL,Lots,Bid,Slip*Pips_Slip,Stop_Loss,TP,0,Magic_Number,0,0);

TP=0; Magic_Number=1;Slip=3;