MT 4 strategy tester question

When I run my EA through the tester over a three month period it survives without a margin call trading .01 lots with $2000. So I assume that for every $2000 I should be able to trade .01 lots. So I ran $4000 at .02 lots, $6000 at .03 lots, $8000 at .04 lots, $10,000 at .05 lots $12,000 at .06 lots and all these survived the three month period without a margin call. Trading $14,000 at .07 lots doesn't survive. In fact, $20,000 at .07 doesn't survive. Can someone please explain what could cause this? Thank you.

Does the lot size change during the backtest?

Ronald,
The initial lot size is .07 and makes additional trades at a multiple of (3). Example, .07 first trade, .21 lots second trade, .63 lots third trade ect. until price goes in my favor x amount of pips and TP's. Then EA goes back to trading a .07 lot again. So EA is placing trades as it should be but I can't figure out why it margin calls at .07 lots with $14000 when it survives .01 lots with $2000.

Maybe it's me, but you're increasing the lot size and account balance in a linear fashion when the lot size grows exponentially.

Ronald,

Are you saying I would have to increase my balance by a multiple of three for every .01 lots I trade to avoid a margin call? If this is the case, why would $6000 at .03 ,$8000 at .04, $10,000 at .05 and $12,000 at .06 all survive the three month period without a margin call?

Look at the maximum drawdown of the three other data points. Do they also line up in a linear fashion?

Graph these two lines:

y = (1/2)x+10
y = x^2

One line is curved, and the other line is straight.

When you start out, you'll see that y = x^2 is lower than y = (1/2)x+10, but when you reach the point: (3.42214438511, 11.7110715081) y = x^2 is higher than y = (1/2)x+10.

In other words, the account balance is not increasing at the same rate the maximum drawdown is increasing. My suspicion is that the maximum drawdown as a percentage of the account balance is increasing.

You're probably right. Thank you Ronald

Ronald,
I've been looking at this some more and it still doesn't make sense to me. I did a little test on a demo trading $2000 @.01 lots and $4000 at .02 lots. Even at my first level trade( using my multi. level EA) the $4000 account used more margin.Why wouldn't it use the same? If this is the case you would be safer to spread your money out over multiple accounts ( but IBFX limits you to 3) and keep your lot size as low as possible.