SkImageDecoder::Factory returned null ... after CopyStream

Question

I have the following code situation:

A function which processes and returns a bitmap images from InputStream

everything is OK up here

private Bitmap loadBitmap(InputStrean is)
{
.....
.....

return BitmapFactory.decodeStream(is, null, o);
}

Before last statement I wanted to copy that stream

private Bitmap loadBitmap(InputStrean is)
{
.....
.....

CopyStream(is, os);

return BitmapFactory.decodeStream(is, null, o);
}

which resulted in the following error "SkImageDecoder::Factory returned null"

public static void CopyStream(InputStream is, OutputStream os)
{
final int buffer_size=1024;
try
    {
        byte[] bytes=new byte[buffer_size];
        for(;;)
        {
          int count=is.read(bytes, 0, buffer_size);
          if(count==-1)
              break;
          os.write(bytes, 0, count);
        }
    }
    catch(Exception ex){}
}

InputStream does not change and yet ... he can be wrong ?