I have backtested a daily EA on various time frames (from M5 to H1) and I am getting different results. The EA in question is SimpleDailyRangeBreakout and simply buys/sells at a % of the previous days range .... so why would I get different results on a daily EA if I backtest at different timeframes ?? It's not just this EA, I've seen it on others too.

SimpleDailyRangeBreakout was not coded for D1 bar especially. This EA is using different calculation. I am using it for H1 timeframe.

As to other EAs so look inside the code: it should be D1 timeframe mentioned. If not so EA should perform differently in different timeframes. But it is mainly related to the trading system. I mean that every EA is manual trading system automazied (automated/coded to be mechanical trading system).

Yes, but my point is that the Daily Range is the same whether you are on M1, H1 OR Daily. So why am I getting different results ? I want to use this EA with a broker who doesn't use MT so I am having to try and replicate it's calculations and this difference between timeframes is causing me problems.

SimpleDailyRangeBreakout Ea is different. This EA is not using daily bar. May be using but the calculation is so difficult for me ...
Thus SimpleDailyRangeBreakout is not the right example for that.

It should be different EAs but I do not know any.
May be FozzyExpert_v1.2 (D1 timeframe only) ...
PriceChannelExpert_v4 (D1 timeframe).

The EA should be coded for D1 close bar. We do not have many EAs like that.