convert to MQL5 , find the error

Hello,

I'm trying to convert this pine script to MQL5. but I can't find the error can someone help me?

 // Pinscript 
C_BodyHi = math.max(close, open)
C_BodyLo = math.min(close, open)
C_Body = C_BodyHi - C_BodyLo

pine_ema(src, length) =>
    alpha = 2 / (length + 1 )
    sum = 0.0 
    sum := na(sum[ 1 ]) ? src : alpha * src + ( 1 - alpha) * nz(sum[ 1 ])

C_BodyAvg = pine_ema(C_Body, 14 )

Here is my conversion to MQL5 that doesn't work:

 double pine_ema( double src[], int length)
{
     double alpha = 2.0 / (length + 1 );
     double sum[];
     ArraySetAsSeries (sum, true );
     ArrayResize (sum, ArraySize (src));
     for ( int i = 1 ; i < ArraySize (src); i++)
    {
         if (i == 1 || IsNaN(sum[i- 1 ]))
            sum[i] = src[i];
         else 
            sum[i] = alpha * src[i] + ( 1 - alpha) * sum[i- 1 ];
    }
     return (sum[ ArraySize (sum)- 1 ]);
}

 double C_BodyHi = MathMax (close, open);
 double C_BodyLo = MathMin (close, open);
 double C_Body = C_BodyHi - C_BodyLo;

 double C_BodyAvg = pine_ema(ArrayCopySeries(C_Body), 14 );