Some brokers use symbol prefix and/or suffix in fx symbols (e.g XXXYYY.mini .XXXYYY). To allow for the EA to take trades, user should under the prefix and/or suffix in the Symbol settings (e.g .mini as suffix/ . as prefix)
Moreover, Brokers have different names when it comes to Metals, Energies.... Gold might be written as GOLD or XAUUSD. User should enter correspondent Symbol for each asset.