@bagheria For backtests, there is a "If Testing" block. Unfortunately with the backtester, OnChart doesn't work with buttons, but OnTick does. So if you want to backtest with it, you need to have an If Testing block, connected to the rest of your logic OnTick.
i.e. This is a old example with just a simple buy button, which works in the backtester.
https://fxdreema.com/shared/jvHegkKHc
Whenever doing backtesting, you should always include some kind of delay, if not random. You're orders in live markets are never instant.
Additionally, any test that's not based on real-ticks or tick-data is not good and shouldn't be taken seriously.
There are still other factors such as how it trades. Does it scalp? Does it have a tight trailing stop? All these things matter. Additionally, you should add commissions to your backtest. Some kind of swaps too if the strategy holds trades through the next day.
Lastly, and most important, just because these things are included, it still doesn't mean it's going to perform the exact same way in live, but it should be a close representation.
To add commissions, you can click this button and input the commissions your broker charges. I can try to find an article to link if it's confusing to you or you can probably find an article in a few minutes on how to do it. 
I messed with creating it a different way and this worked just as well with less code . The if statement just checks the current status and if its on, then it toggles the button. Otherwise it does nothing. There is no custom function to make or anything.
// Global Variables, includes
#include <WinUser32.mqh>
#import "user32.dll"
int GetAncestor(int, int);
#define MT4_WMCMD_EXPERTS 33020
#import
// Main Code
if (IsTradeAllowed()){
int main = GetAncestor(WindowHandle(Symbol(), Period()), 2/*GA_ROOT*/);
PostMessageA(main, WM_COMMAND, MT4_WMCMD_EXPERTS, 0);
}