Undeclared Identifiers for built in functions

I have included Trade.mqh in my code, compiler is able to access it. I have opened it in the editor and searched for OrderModify() function and it is there. When I ran a compiler (MQL5) it still flags OrderModify() as undeclared identifier, what could be the issue because this is recurring oftenly
Francis cheruiyot:

You should instantiate an object of CTrade Type first:

#include <Trade\Trade.mqh>
CTrade trade;