Quick EA Question: Strategy Tester, BarOpen v Tick

Howdy Folks,

I have an EA, which only executes order open/close on BarOpen

int start()
{
bool OpenBar=true;
if(EnterOpenBar) if(iVolume(NULL,0,0)>1) OpenBar=false;
if (OpenBar)
{
//open or close order
}
}

My question:
Why does my EA preform excellently when using Strategy Tester on bar open data, and blows on tick data.
Am I missing something here?

Thanks.
K.

Volume is not a good way to check for a new bar; use time.

Thanks,
I will change the code for comparison.
K.