Incorrect baseline date determination for ERS

Hi Exports

I have the below scenario and need your inputs.

We have a requirement that the GR document date should be used as a base line date for the payment due date determination.

We use the payment term, which is configured such that the "document date" should be defaulted as "Baseline date ".

When the ERS function is executed (MRRL),the GR document date is getting populated to the invoice document "document date". But 

system always defaults the current date as the base line date for payment ,not the document date (GR or Invoice)

Is this standard SAP behavior or Am i missing any settings to populate the GR document date / Invoice document date ?

Regards

Gobinathan G