Change User Password from Oracle Form

I have created a change password form in Oracle Developer 2000 in order to fascilitate the user to change its password from this form instead of SQL/SQLPlus environment. But I am facing a problem in implementation of my this idea. The problem is that I am unable to issue the “Alter User” command from this form. For this purpose I have used “Forms_DDL” built-in. But Oracle Developer refused to execute this command. So it is requested that if someone know about it to change password from oracle form then he may kindly be guide me to solve my this dilemma.
I shall be highly obliged for this.
My email address is
hawk1@mul.paknet.com.pk

Thanks.