SAP PPM 6.1 S4Hana BP creation W/O HR integration

Hi SAP experts.

I can create resources BP for PPM and I´m using the BP perfect. (No HR interfase)

The problem is when I need asociate the SAP USER to the BP, the field is disable and after work in the custo of BP is imposible open this field.

There are same way to asociate the BP and the user?

Regards.

Claudio