concepts of Retroactive Acctg.

Hi,

While doing some testing on QAS I got few errors/ warnings in yellow.

RA run too early for Payroll area IL

Earliest retroactive accounting period: 2008 01

Retroactive accounting date for employee: 01.03.2008

Why is this error coming and where is the retroactive acctg date maintained for the Employee?

Please tell me the concepts of Retroactive Acctg.