Tick data mismatch, ticks discarded when backtesting.

Hello. When I attempt to backtest using real ticks, I get several errors saying that there are tick mismatches and that ticks are being discarded. I tried downloading only data from last year, it still didn't work. I tried to import data into a custom symbol and I couldn't. Is there anyway I can rectify this? I attempted this on EURUSD on the daily timeframe.