0FIAR_C03_Q0005 - Days Overdue Analysis reconciliation with ECC

Hi,

I am trying to reconcile the ageing report data with ECC trans FBL5N.

The total value is matching with current and previous key due dates. What i want to check is the values of 1-30 days, 31-60 days etc.

The logic i am using is for eg for 1-30 days value calculation from FBL5N. i am taking customer ageing open items for yesterdays date i.e 11.10.2014

and then going in reverse 30 days - 12.09.2014 taking the open items for customer on this day and then subtracting to get value of customer ageing

(1-30) days. However the data of this method and BW customer ageing report doesnt seem to be matching.

Is there any other method to reconcile the data or am i making some mistake ??

Pls help me.

Thanks.