How to switch timeframes in an EA

[Forex Trader]

And another question,

I have a function and I want to switch the timeframe used in the variables depending on the value of another parameter.

if((MathAbs(FastTrend-SlowTrend)<RangePoint*Point) && (TFTime!=iTime(Symbol(),PERIOD_M15,1)))
             {
             RangePreFetch();
             TFTime=iTime(Symbol(),PERIOD_M15,1);
             }
      if((MathAbs(FastTrend-SlowTrend)>RangePoint*Point) && (TFTime!=iTime(Symbol(),PERIOD_H1,1)))
             {
             TrendPreFetch();
             TFTime=iTime(Symbol(),PERIOD_H1,1);
             }

RangePreFetch and TrendPreFetch are the same function, just with different timeframes.

Why doesn't this work?