Customizing error in work schedule rule ????

Hi Gurus,

When i intend to create a work schedule in PT01, it gives the following error message " Customizing error in work schedule rule 2 IN 01 KM01"

where,

2 - Employee Subgroup grouping

IN - Holiday Calendar

01 - Personnel Subarea Grouping

KM01 - Work Schedule.

Can anyone help me to fix that and proceed further.

Thanks in Advance.