Bar shifting and iLow/iLowest only work on full hours? (10pm, 11pm ...)

Why are you not trying to test your code.

Then you may have found this:

   string fromM = IntegerToString(fromMinute);
   string toM = IntegerToString(fromMinute);

I have not checked all your code, because i think you have to do it.

Print your values or use the debugger.

I checked it but didn't found something... - But thank you a lot!

I will try it and check it again! - Sometimes you are just blind... hehe 

Okay... I think, I found my error... But nothing is wring in the code!

E.g.: If I type from 12-17, the EA marks a diffrent/wrong area... - 17 shifts for the 17 o'clock is right, but not 37 for 12 o'clock...
Does anybody know the solution?

The time outputs are right... So iBarShift is wrong or I just don't use it right... - Can that be? 

1. FrazeColder: E.g.: If I type from 12-17, the EA marks a diffrent/wrong area... - 17 shifts for the 17 o'clock is right, but not 37 for 12 o'clock...
   
   12-17 is 5 hours. 5 hours on the M15 is 20 bars. 17 + 20 = 37. Exactly correct.

   ---

2. string fromH = IntegerToString((fromHour));
   string fromM = IntegerToString(fromMinute);
   string toH = IntegerToString((toHour));
   string toM = IntegerToString(fromMinute);
   :
   string point = ".";
   string spacer = " ";
   string doublepoint = ":";
   string year = IntegerToString(Year());
   string month = IntegerToString(Month());
   string day = IntegerToString(Day());
   
   StringAdd(year, point);
   StringAdd(month, point);
   StringAdd(day, spacer);
   StringAdd(fromH, doublepoint);
   StringAdd(toH, doublepoint);
   
   string fromFinal = year+month+day+fromH+fromM;
   string toFinal = year+month+day+toH+toM;
   :
   datetime lowest = StrToTime(fromFinal);
   datetime highest = StrToTime(toFinal);
   

   Simplify your date handling

   datetime lowest  = StrToTime(StringFormat("%i:%i", fromHour, fromMinute) );
   datetime highest = StrToTime(StringFormat("%i:%i",  toHour,    toMinute) );

   Or simplify your date handling by not using strings.

   #define HR2400 86400
   int     time(datetime when=0){
      return int(when == 0 ? TimeCurrent() : when) % HR2400;                   }
   datetime   date(datetime when=0){
      return datetime( (when == 0 ? TimeCurrent() : when) - time(when) );      }
   datetime   tomorrow(datetime when=0){    // Weekends not accounted
      return date(when) + HR2400;                                              }
   /// Returns previous trading day.
   datetime   yesterday(datetime when=0)    /**< Previous relative to
                                                    * when. */{
      if(when==0) when = TimeCurrent();
      int      iD1   = iBarShift(NULL, PERIOD_D1,  when);   // Find today.
      return iTime(NULL, PERIOD_D1, iD1 + 1);               // Return yesterday.
   }
   //////////////////////////////////
   datetime now     = date();
   datetime lowest  = now + fromHour * 3600 + fromMinute * 60;
   datetime highest = now +   toHour * 3600 +   toMinute * 60;
   

Okay, then another example...

This time I typed from 12 to 16 o'clock.

The EA says that I need to shift 8 bars, to get to the 16 o'clock bar and 24 shifts to 12 o'clock. That's correct!
-> So the range for the lowest and highest price in this time should be between 8 till 24 bar shifts. Correct?

But why the hell is the EA saying, that the highest bar is at 25 bar shifts and the lowest by 31? - That's totally wrong!!!

And to you code: So I don't need 4 input variables for the time, just two. Right
For example: 12:15 and 16:30 - Right? - Because the "command" %i:%i splits the string at ":".
But why I need 4 variables then in the code?

datetime lowest  = StrToTime(StringFormat("%i:%i", fromHour, fromMinute) );
datetime highest = StrToTime(StringFormat("%i:%i",  toHour,    toMinute) );

Check the parameters of your function calls.

   int lowestShifts = iLowest(NULL, 0, 1, leftToShiftLowest, leftToShiftHighest);
   int highestShifts = iHighest(NULL, 0, 2, leftToShiftLowest, leftToShiftHighest);

There is no from - to. There is only count and start.

Ohhh... so I thought, that I start stands for the beginning of the shifting... :/

Any idea, how I can fix this problem? - I only want to check a specified area... So if we have 17:45 and I type fron 10-17 o'clock, I don't want, that oLowest/iHighest checks also the time area between 17 o'clock and now (17:45)... 

int lowestShifts = iLowest(NULL, 0, 1, leftToShiftLowest, leftToShiftHighest);
int highestShifts = iHighest(NULL, 0, 2, leftToShiftLowest, leftToShiftHighest);

1. You code it properly. As eddie already said, there is only count and start no from and to. When in doubt, think!
   

   int lowestShifts  =  iLowest(NULL, 0, MODE_LOW,  leftToShiftLowest - leftToShiftHighest + 1, leftToShiftHighest);
   int highestShifts = iHighest(NULL, 0, MODE_HIGH, leftToShiftLowest - leftToShiftHighest + 1, leftToShiftHighest);

2. Don't hard code numbers, use the symbolic constants Series Array Identifiers - Indicator Constants - Standard Constants, Enumerations and Structures - MQL4 Reference

Thank you a Lot WHRoeder!
But if it is possible could you help me by two more questions?

1. I already wrote:
"And to you code: So I don't need 4 input variables for the time, just two. Right

But why I need 4 variables then in the code?"

datetime lowest  = StrToTime(StringFormat("%i:%i", fromHour, fromMinute) );
datetime highest = StrToTime(StringFormat("%i:%i",  toHour,    toMinute) );

2. I wanna try to change my system to a fully automatic system, so I don't need to input the times anymore...
But my problem is to "program the future". For example:

I have some fix times when I'am using my EA. We say, let's use 10am-12am. How can I programm the EA so, that the EA is looking every day, between 10am to 12am for the highest and lowest price at the market?
The specified range which I must enter in the EA at the moment!