I am receiving this error (CS0161), why am I getting it? : <p>coding newbie here. I was practicing my C# to make a Caesar Cipher encoder. When I was making a method to encrypt my message, I got this error. (see it below).</p>

<p>Why am I getting this error?</p>

<p>I've tried to change the method return type to void. But then it says that it cannot convert void type to bool. Can I have some help here?</p>

<pre class="lang-cs prettyprint-override"><code>using System;

namespace CaesarCipher
{
  class Program
  {
    static void Main(string[] args)
    {
      Console.WriteLine(Encrypt("hello"));
    }

    static string Encrypt(string message)
    {
      char[] alphabet = new char[] {'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z'};

      string secretMessage = message.ToLower();
      char[] secretMessageChar = secretMessage.ToCharArray();

      char[] encryptedMessage = new char[secretMessageChar.Length];

      for (int i = 0; i &lt; secretMessage.Length; i++)
      {
        if (!Char.IsLetter(secretMessageChar[i]))
        {
          continue;
        }

        char letter = secretMessageChar[i];
        int caesarLetterIndex = (Array.IndexOf(alphabet, letter) + 3) % 26;

        char encryptedCharacter = alphabet[caesarLetterIndex];

        encryptedMessage[i] = encryptedCharacter;

        return String.Join("", encryptedMessage);
      }
    }
  }
}
</code></pre>

<p>I expected the output to be something like 'khoor', but instead, it says this:
Program.cs(12, 19): error CS0161: 'Prog)': not all code paths return a value</p>
