MD5\SHA256 hash troubles

[vertexpipeline]

After hashing via MD5, SHA256 returns wrong results.
Example:

var file = "C:\\Games\\StarCraft II\\SC2Data\\data\\data.008";
var stream = File.Open(file, FileMode.Open);
var startTime = DateTime.Now;
var hashMd5 = MD5.Create().ComputeHash(stream);// hashing MD5 
var end = DateTime.Now - startTime;
WriteLine($"Md5 hash time - {end}, hash = {Convert.ToBase64String(hashMd5)}"); // ~15 sec.

var hashSha256 = SHA256.Create().ComputeHash(stream);//~ 0.5
end = DateTime.Now - startTime;
WriteLine($"SHA256 hash time - {end}, hash = {Convert.ToBase64String(hashSha256)}"); //returns wrong hash

var hashSha512 = SHA512.Create().ComputeHash(stream); // it is too
end = DateTime.Now - startTime;
WriteLine($"SHA512 hash time - {end}, hash = {Convert.ToBase64String(hashSha512)}");

The example returns results after 15 seconds average, but why SHA256 returns result after ~ 0.5 sec.
There is a correct hash:

var file = "C:\\Games\\StarCraft II\\SC2Data\\data\\data.008";
var stream = File.Open(file, FileMode.Open);
var startTime = DateTime.Now;
var hashSha512 = SHA512.Create().ComputeHash(stream);//hashing 1:30 min.
var end = DateTime.Now - startTime;
WriteLine($"SHA512 hash time - {end}, hash = {Convert.ToBase64String(hashSha512)}");//returns correct hash

Thanks.

[stephentoub]

You're not resetting the stream back to the beginning, so the first hash hashes the file, and the next ones have no data to hash.

[vertexpipeline]

oh, thanks. It's works. I don't know, why i didn't it...