cudaMemcpy logical problem with size

Hi all I have one little problem with cudaMemcpy…

cutLoadPPMub("/home/eddy/Bunkove/lena.ppm",(unsigned char **) &host_image, &width,&height);
size=widthheight3
unsigned char device_image;
unsigned int cpysize=size
sizeof(unsigned char);
cudaMalloc((void **) &device_image, cpysize);
cudaMemcpy(device_image, host_image, cpysize, cudaMemcpyHostToDevice);

But nothing happend… device_image was still empty and cuda did not write any error…

HEEEELP pls… :)