Gaussian filter

[g00se]

I'm writing a code for Gaussian filter. It works kinda strange. It only changes brightness of an image, but do not blur image. Here is my code:

     // Count mask 3x3
     if (size == 1) {
         for (row=-1; row<=1; row++) {
             for (col=-1; col<=1; col++) {
                 midCalkulation = -((pow(col, 2) + pow(row, 2))/(2*pow(sigma, 2)));
                 kernel3x3[row+1][col+1] = (1/(2*M_PI*pow(sigma, 2)))*exp(midCalkulation);
                 
             }
         }
     }

     // Image convolution with filter mask
     if (size == 1) {
         for(row=1; row<height-1; row++) {
             for(col=1; col<width-1; col++) {
                 midSum=0;
                 for(int i=-1; i<=1; i++) {
                     for(int j=-1; j<=1; j++) {
                         midSum += pixels[(row+i)*width + (col+j)]*kernel3x3[i+1][j+1];
                     }
                 }
                 filteredPixels[row*width + col] = midSum;
             }
         }
     }

I can't see where I'm making a mistake. Little help needed, please. Thank in advance.