A big Difference between result from EA Test

Hi

i try test a EA in 1 1 2014 to 7 1 2014 and ea work like a charm without any loos trade. BUT when i try test from 1 1 2013 to 12 1 2013 result fully difference and result very bad

Something that has surprised me is big difference in result test in that two period 

What I would like to ask why in first 6 mount 2014 it is awesome but in before that my EA change Behavior??

It is possible Brokers change any candle in past?!! 

Pair: USD/JPY 

Thanks
(Sorry for about my English :) );