exception in bitmap(stream*) constructor

[Soja]

Hallo,

i have following problem

I dry to create a Bitmap from Byte[], i use the Bitmap(Stream*) constructor,
but a exception rise there

Code:

unsigned char dest __gc[] = new unsigned char __gc[1024*1280];

Marshal::Copy(p image,dest,0, 1024*1280 );

MemoryStream * mem = NULL;

mem = new MemoryStream(de st);

MemoryStream * str = new MemoryStream();

int size = 1024*1280;

str->Write(dest, 0, size);

System::Drawing ::Image *image = NULL;

image = new Bitmap(str);

Bitmap bmp = new Bitmap(mem );