Array too small for DCT transformation in LabWindows CVI

Question

I have been doing a school project about digital watermark based on DCT using LabWindows CVI 2012. I divide an image with the size of 512 * 512 into many 8 * 8 blocks, and then use DCT transformation on each of them. But there is an error message that the input array is too small. I don't know which part I do wrong, can someone help me with this?

int CVICALLBACK Img_to_array (int panel, int control, int event,
        void *callbackData, int eventData1, int eventData2)
{
    char *Arraydata;
    Point point;
    int x,y;
    PixelValue pixelvalue;
    
    imaqGetImageSize(SourceImage,&width,&height);
    
    switch (event)
    {
        case EVENT_COMMIT:
        Arraydata = imaqImageToArray (SourceImage, IMAQ_NO_RECT, NULL, NULL);

        for(y=0;y<height;y++)
        {
            for(x=0;x<width;x++)
            {
                point.x=x;
                point.y=y;
                imaqGetPixel (SourceImage,point,&pixelvalue);
                Arraydata[y*width+x]=(char)pixelvalue.grayscale;
            }
        }
        
        //-----------divide into 8*8 block and DCT transform-------------
        char block[8][8];
        char dct_block[8][8];
        int i,j,row,column;
        for(x=0;x<width/8;x++)
            for(y=0;y<height/8;y++)
            {
                for(row=0,j=0;row<8;row++,j++)
                    for(column=0,i=0;column<8;column++,i++)
                        block[row][column]=Arraydata[(x*8+i)+(y*512*8+j*512)];
                DCT2D (block, 8, 8, dct_block);
                
                for(row=0,j=0;row<8;row++,j++)
                    for(column=0,i=0;column<8;column++,i++)
                        Arraydata[(x*8+i)+(y*512*8+j*512)]=dct_block[row][column];
            }
        //---------------------------------------------
        
        
        imaqArrayToImage (DestImage, Arraydata, width, height);    
        imaqSetWindowTitle (1,"AfterDCT result"); 
        imaqMoveWindow (1,imaqMakePoint(150,260));
        imaqDisplayImage (DestImage,1,TRUE); 
        break ; 
    }
    return 0;
}

Here is the error info: https://i.stack.imgur.com/jemUk.png

Here is the function DCT2D info: https://zone.ni.com/reference/en-XX/help/370051AG-01/cvi/libref/cvidct2d/