How to Hex Encode a SHA-256 Hash

How to Hex Encode a SHA-256 hash properly in C#?

private static string ToHex(byte[] bytes, bool upperCase)
{
    StringBuilder result = new StringBuilder(bytes.Length * 2);

    for (int i = 0; i < bytes.Length; i++)
        result.Append(bytes[i].ToString(upperCase ? "X2" : "x2"));

    return result.ToString();
}

private string hashRequestBody(string reqBody)
{
    string hashString;
    using (var sha256 = SHA256Managed.Create())
    {
        var hash = sha256.ComputeHash(Encoding.Default.GetBytes(reqBody));
        hashString = ToHex(hash, false);
    }

    MessageBox.Show(hashString);
    return hashString;
}

I did this, but the result is different with bank's sandbox I worked with.

TEST DATA:

{"CorporateID":"BCAAPI2016","SourceAccountNumber":"0201245680","TransactionID":"00000001","TransactionDate":"2017-09-13","ReferenceID":"refID","CurrencyCode":"IDR","Amount":"10000","BeneficiaryAccountNumber":"0201245681","Remark1":"Transfer Test","Remark2":"Online Transfer"}

Bank's sandbox result: e9d06986c1ed6b063bf59aa873030013725c518631deef2b2147e614017c2141

Mine: 1c83acc42cf905ca8afba27ef0640c70ad2856a366b57c17cf16f2894327676e