System tester and expert advisor results do not match

This is a known concern.  Some people consider this a bug, but the Equis product developers say it is working as designed.  Really, both sides can be argued. What's more important here is that you understand why it happens and what it means…

When you run an equity test, the program calculates the number of shares you can purchase. For example, I have set my initial equity at $10000 and my setting is to use 100% of available equity. Today I get a buy signal and at the close price the value of the share is $10. The program calculates what I can buy on the next day at the open- 1000 shares.  Now, the next day at the open there is a gap up or the price opens higher than 10 dollars for any reason... the program will say ok, yesterday I had an order to buy 1000 shares so 1000 * 10.000001 is greater than $10000 so I can't buy and therefore cancel the order.

Two suggestions:

1 - Use points only tests... there are many reasons why.

2 - If you really want equity test use less than 100% of your initial investments, then set it at 90-95%.