Unable to manual enrol: enrol_manual_enrol_users

Hi

I tried to enrul a user with c# and get the message: Missing required key in single structure: userid

I do it the same way as creating courses or users, so I think the format is correct.

Before the enrolement I did a 'core_user_create_users' with withcreatepassword and I activated the user.

There is another topic: https://moodle.org/mod/forum/discuss.php?d=341946

Can it be a problem with permissons?

Thanks for Help

Hajo