SOP - Error while creating planning hierarchy

Hi,

For SOP, I have created info structure with following steps

1. Enter Info Structure between S501 to S999 and with application 41.

2. Chose characteristics and key figures.

3.Generate info structure.

4. Save

Then I have created planning type.

However, while creating Planning Hierarchy, when i enter info structure, System shows following error.

"Info structure S508 lacks the necessary structure"

Can any body help me regarding this?

Regards,

Samir Wadajkar