UDO Form doesn't open

Hi experts,

I created a UDO:

1) Two tables (Document and Document Rows)

2) Did the registration of the object

After that, the new option is shown in menu.

The problem is: when I am configuring the second step, if I choose Header_Line Style, the form doesn't open. The same doesn't happen when I choose Matrix Style.

Can anyone help me?

Thanks a lot,

Joana Silva