Please help me find the bug in 5 lines of MQL4 code

I need help with a small piece of code that calculates the moving average of the Williams Percent Range indicator.

Here is the code:

         {
            WPRArray[j] = iWPR(symbol, WPR_Timeframe, WPR_Period, j);
         }
         double WPR_Average = iMAOnArray(WPRArray, 0, WPR_MAPeriod, 0, WPR_MAMethod, 0);
         
         WPR = DoubleToString(WPR_Average, 0);

It gives different values on the indicator on the chart and the value in the variable calculated for WPR, e.g.

Here the value on the indicator is -52,4541 where the value in the Variable WPR = -73 (rounded off)

And here is another example:

Value of the indicator = -63.5457 but the variable has the value -41(rounded off)

I have researched the issue and found that there is a 12 hour difference where the value in the variable lags the value of the indicator. 

Here is a chart over 20 hours of the values of the indi and the var to illustrate: