Login problems with encrypted passwords

I have some login code that works fine on several local machines, but always fails when uploaded. I think it has something to do with encryption. Here is the Submit_Click event which when the code is uploaded always sets newUser to null, so I always get 'Login failed'. PhilePrincipal.ValidateLogin is called to set the value of newUser and this involves encryption (see code below). That is the only reason I can think of why it is not working. Any ideas?

private void Submit_Click(object sender, System.EventArgs e)
{
PhilePrincipal newUser = PhilePrincipal.ValidateLogin( EmailAddress.Text, Password.Text );
if (newUser == null)
{
LoginResult.Text = "Login failed for " + EmailAddress.Text;
LoginResult.Visible = true;
}
else
{
Context.User = newUser;
FormsAuthentication.SetAuthCookie( EmailAddress.Text, true );
Response.Redirect("default.aspx");
}
}

public static PhilePrincipal ValidateLogin(string emailAddress, string password)
{
Configuration.ModuleSettings moduleSettings = Configuration.ModuleConfig.GetSettings();
int newID;
byte[] cryptPassword = EncryptPassword( password );

Data.User dataUser = new Data.User( moduleSettings.ConnectionString );
if ( (newID = dataUser.ValidateLogin(emailAddress, cryptPassword)) > -1 )
return new PhilePrincipal( newID );
else
return null;
}

public static byte[] EncryptPassword(string password)
{
UnicodeEncoding encoding = new UnicodeEncoding();
byte[] hashBytes = encoding.GetBytes( password );
// compute SHA-1 hash.
SHA1 sha1 = new SHA1CryptoServiceProvider();
byte[] cryptPassword = sha1.ComputeHash ( hashBytes );
return cryptPassword;
}


Cheers,

Mike