I have a problem with Strategy Tester of MT4,
1.I test an EA by Strategy Tester on one currency pair with spread set 14 and result is good, but when repeat test with same settings and with 13 spread, the account has been called!
2.another problem is when I test an EA with two different brokers, I see almost different result, what wrong?
2. Test EA with different brokers = different results
This is one of the golden truths about brokers! An EA might perform brilliantly with one broker and on another broker just produce losses - this is due to different spreads (even if you set the tester to say spread = 15) because even the historical data from different brokers are different even for the same currency pair.
You will soon uncover another golden truth - testing during the week while the markets are open and testing over a weekend when the market is closed with the same broker will also give you different results (even with the same data) - do not ask me why - just something that I experienced when I do back testing of EAs.
To answer the question in the second "golden truth" ... the reason is the broker varies the spreads between the Asian market hours (highest spread), European Market hours (lower spread), and US Market hours (lowest spread). There are free tools to put the current spread on a corner of your chart so you know the actual current spread being charged by your broker. Sometimes even within one market hours set the spread will vary.
When you use system tester and with some inputs, you can change spread settings.... all this gives you very different results.