OnCalculate function not found in custom indicator

Code:

//+------------------------------------------------------------------+
//|                                                        sumon.mq4 |
//|                                  Copyright 2024, Asif Iqbal Sumon |
//|                                             https://www.mql5.com |
//+------------------------------------------------------------------+
#property copyright "Asif Iqbal Sumon"
#property link      "https://englishact.com"
#property version   "1.00"
#property indicator_separate_window
#property indicator_buffers 4
#property indicator_color1 Lime      // Verified Support
#property indicator_color2 Orange    // Weak Support
#property indicator_color3 Red       // Verified Resistance
#property indicator_color4 DarkRed   // Weak Resistance

//--- indicator buffers
double VerifiedSupportBuffer[];
double WeakSupportBuffer[];
double VerifiedResistanceBuffer[];
double WeakResistanceBuffer[];

//--- input parameters
input int lookBackPeriod = 50; // Look back period for support/resistance detection
input double verifiedLevelThreshold = 20; // Threshold for verified levels

//+------------------------------------------------------------------+
//| Custom indicator initialization function                           |
//+------------------------------------------------------------------+
int OnInit()
{
    // Buffers
    SetIndexBuffer(0, VerifiedSupportBuffer);
    SetIndexBuffer(1, WeakSupportBuffer);
    SetIndexBuffer(2, VerifiedResistanceBuffer);
    SetIndexBuffer(3, WeakResistanceBuffer);
    
    // Set names for buffers
    IndicatorShortName("Support and Resistance Levels");
    SetIndexLabel(0, "Verified Support");
    SetIndexLabel(1, "Weak Support");
    SetIndexLabel(2, "Verified Resistance");
    SetIndexLabel(3, "Weak Resistance");

    return(INIT_SUCCEEDED);
}

//+------------------------------------------------------------------+
//| Custom indicator iteration function                                |
//+------------------------------------------------------------------+
int OnCalculate(const int rates_total,
                const int prev_calculated,
                const datetime &time[],
                const double &open[],
                const double &high[],
                const double &low[],
                const double &close[],
                const long &tick_volume[],
                const long &volume[],
                const double &spread[])
{
    // Ensure that we have enough rates
    if (rates_total < lookBackPeriod)
        return 0;

    // Clear buffer values
    ArraySetAsSeries(VerifiedSupportBuffer, true);
    ArraySetAsSeries(WeakSupportBuffer, true);
    ArraySetAsSeries(VerifiedResistanceBuffer, true);
    ArraySetAsSeries(WeakResistanceBuffer, true);

    for (int idx = 0; idx < rates_total; idx++)
    {
        VerifiedSupportBuffer[idx] = EMPTY_VALUE;
        WeakSupportBuffer[idx] = EMPTY_VALUE;
        VerifiedResistanceBuffer[idx] = EMPTY_VALUE;
        WeakResistanceBuffer[idx] = EMPTY_VALUE;
    }

    for (int i = lookBackPeriod; i < rates_total; i++)
    {
        double highPrice = high[i];
        double lowPrice = low[i];
        int countSupport = 0;
        int countResistance = 0;

        // Count support and resistance levels
        for (int j = 1; j <= lookBackPeriod; j++)
        {
            if (low[i - j] <= lowPrice) countSupport++;
            if (high[i - j] >= highPrice) countResistance++;
        }

        // Identify zones
        if (countSupport >= verifiedLevelThreshold)
            VerifiedSupportBuffer[i] = lowPrice;
        else
            WeakSupportBuffer[i] = lowPrice;

        if (countResistance >= verifiedLevelThreshold)
            VerifiedResistanceBuffer[i] = highPrice;
        else
            WeakResistanceBuffer[i] = highPrice;
    }
    
    return rates_total;
}
//+------------------------------------------------------------------+

Errors:

OnCalculate function declared with wrong type or/and parameters sumon.mq4 50 5

OnCalculate function not found in custom indicator 1 1

Replacing

 const double &spread[])

to

 const  int &spread[])

is solving the problem