Landing Page custom URL - not works with forms

Hi,

I would like to ask you if this is just default settings for Eloqua, or I missed something.

Problem:

1. I created the Form with Thank You page redirection after submission
2. I prepared the Thank You landing page with Vanity URL (custom url: www.123.com/123)
3. In Processing step, I did choose the LP that I have just created
4. After Submission, the customer is redirect to this LP but.... with different ULR then I have customized.
5. After short discussion with Oracle Support, I got info that I need to upload special picklist to link the Thank you page with custom URL...