SQL & PL/SQL

Hello everyone!

I'm writting a simple procedure that is adding user to database and I have some problems. My table and procedure looks like this:

CREATE TABLE account 
(
  id NUMBER(6,0) PRIMARY KEY, 
  login VARCHAR2(16) NOT NULL, 
  password VARCHAR(255) NOT NULL,
  email VARCHAR(25) NOT NULL,
  register_data DATE,
  last_seen DATE,
  login_failed NUMBER(5,0)
);

And procedure:

CREATE PROCEDURE add_user (pid IN NUMBER, plogin IN VARCHAR2, ppassword IN VARCHAR, pemail IN VARCHAR)
IS 
  encryptedpassword VARCHAR(255);
BEGIN
  encryptedpassword := MD5(ppassword);
  INSERT INTO account(id, login, password, email)
  VALUES (pid, plogin, encryptedpassword, pemail);
END add_user;

After compilation I've got these errors:

• Error(5,3): PL/SQL: Statement ignored
• Error(5,24): PLS-00201: identifier 'MD5' must be declared

What is wrong with this code?
And yes, I know that md5 is bad and now nobody should use it, but this is only for me.