Lock/Unlock user account

Greetings.

I am developing a Java applet that will chage user information, and the user account information as well. I am able to modify all fields in the user information and assign the user to roles as well. However, when I try to lock or unlock the user account, the call seems to hang. Can anyone assist? Below is what I am doing:

IUserAccountFactory userAccountFactory = UMFactory.getUserAccountFactory();

IUserAccount userAccount = userAccountFactory.getUserAccountByLogonId(myLogonId);

// to lock the account:

userAccount.setLocked(true,IUserAccount.LOCKED_BY_ADMIN);

// to unlock the account:

userAccount.setLocked(false,IUserAccount.LOCKED_NO);

Thanks,

Bassam H.