Help me understand a warning.

I'm trying to run this function, is made for custom priceseries, basically input are:

-Price applied to (close,low,high ect)

-index of shift 

-open,close,high,low from OnCalculate

this is the function. 

enum Applied_Price       // Type of constant
  {
   Price_Close,          // Close
   Price_Open,           // Open
   Price_High,           // High
   Price_Low,            // Low
   Price_Median,         // Median Price (HL/2)
   Price_Typical,        // Typical Price (HLC/3)
   Price_Weighted,       // Weighted Close (HLCC/4)
   Price_Simple,         // Simple Price (OC/2)
   Price_Quarter,        // Quarted Price (HLOC/4) 
   Price_Trendfollow,    // TrendFollow_1 Price 
   Price_Trendfollow05   // TrendFollow_2 Price 
  };

//+X================================================================X+   
//| PriceSeries() function                                           |
//+X================================================================X+ 
double PriceSeries
 (
  Applied_Price appliedprice, // Price constant
  uint   bar, // Index of shift relative to the current bar for a specified number of periods back or forward
  const double& Open [],
  const double& Low  [],
  const double& High [],
  const double& Close[]
 )
//PriceSeries(appliedprice, bar, open, low, high, close)
//+ - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -+
 {
//----+
  switch(appliedprice) 
   {
    //----+ Price constant from enum Applied_Price
    case  0: return(Close[bar]);
    case  1: return(Open [bar]);
    case  2: return(High [bar]);
    case  3: return(Low  [bar]);
    case  4: return((High[bar] + Low[bar])/2.0);
    case  5: return((Close[bar] + High[bar] + Low[bar])/3.0);                                                                 
    case  6: return((2*Close[bar] + High[bar] + Low[bar])/4.0);
        
    //----+                            
    case  7: return((Open[bar] + Close[bar])/2.0);
    case  8: return((Open[bar] + Close[bar] + High[bar] + Low[bar])/4.0);     
    //----                                
    case 9: 
            {
             if(Close[bar] > Open[bar])return(High[bar]);
             else
              {
               if(Close[bar] < Open[bar])
                    return(Low[bar]);
               else return(Close[bar]);
              } 
            }
    //----         
    case 10: 
            {
             if(Close[bar] > Open[bar])return((High[bar] + Close[bar])/2.0);
             else
              {
               if(Close[bar] < Open[bar])
                    return((Low[bar] + Close[bar])/2.0);
               else return(Close[bar]);
              } 
             break;
            }
    //----
    default: return(Close[bar]);
   }
//----+
return(0);
 }

But i do get this error:

Can't figure it out.