Line cannot contain multiple account sources

Hi,

We have created PO which even include Freight amount. We have Interface which is populating these details on AP Interface table and we are running Payables Import Program to push data to AP.

But we see that Account Details are not getting populated for Freight line.

The Difference what i observed from other lines was that, this Freight line did not have PO number and PO Line number details. So when I Populate that in the Interface and try to push it to AP the  I am getting below Error. Can you please tell where is it looking for Account details?