Create business partner with role 'Internet User' via BP

Hi,

We want to create business partner with role 'BUP005 Internet User'

for purpose to link with created early user su01.

It's work via isauseradm application, Web UI.

Now I want to create new role 'BUP005 Interner user' via GUI. I started Tcode BP.

I filled USERNAME, password, roles. I tried to save BP.

I got this error:

Enter the Internet user

Message no. R11214

You have maintained attributes (logon data, roles and/or fixed values) for the Internet user, without having entered the Internet user itself.

But,

Field 'INTERNETUSER' is not changeble.

?

Denis.