User credential check in a NAV three tier environment

Hi all,
As you all probably know you can validate an user password by the following code:

IF recUser.GET(codUser) THEN BEGIN
recUser2."User ID" := recUser."User ID";
recUser2.VALIDATE(Password,txtPassword);
IF recUser2.Password <> recUser.Password THEN
ERROR('Password is incorrect')
ELSE
ERROR('User validated');
END;

But this procedure doesn’t work when you pass the user and password using the Dynamics NAV Web service. The result is that the password from the recUser is something like ~%$@&amp;%!$#, and after validating the txtPassword it still shows me the password. So the encryption does not work.

Does anyone have any idea what's this all about, and is there a solution? Is it the three tier environment why the encryption does not work?

Thanks in advance.

Greetings,
Don