TimeFrame object bug ?

Hello,

I tried to make a method that converts seconds to the closest timeframe (rounded down), here is the code (only goes to m3 at the moment) :

            // Seconds to Timeframe
            public static TimeFrame Timeframe(double seconds);
            {               
                if(seconds - 60 >= 0 && seconds - 120 < 0)
                    return TimeFrame.Minute;
                else if(seconds - 120 >= 0 && seconds - 180 < 0)
                    return TimeFrame.Minute2;
                else if(seconds - 180 >= 0 && seconds - 240 < 0)
                    return TimeFrame.Minute3;
            }

But I get compiling error...

I think I don't understand very well the timeframe object, I already tried to do it by creating an object like this :

            // Seconds to Timeframe
            public static TimeFrame Timeframe(double seconds);
            { 
                TimeFrame timeframe = new Timeframe();

                if(seconds - 60 >= 0 && seconds - 120 < 0)
                    return timeframe.Minute;
                else if(seconds - 120 >= 0 && seconds - 180 < 0)
                    return timeframe.Minute2;
                else if(seconds - 180 >= 0 && seconds - 240 < 0)
                    return timeframe.Minute3;
            }

But it still doesn't work.

I thought of returning a string like "Minute" or "Minute2" but I'm not sure if it would work with GetSeries, can you tell me if it works ?

How can I make such method ?

Thanks.