Problem during ML81N

Hi,

I have the following issue:

A PO for services has been create with an amount of 2.552,00.

There are two service lines 10 and 20 with the same activity number and the same amount 1.276,00.

When the user posts the service entry sheet and select the activity with the Service sel. button, for both lines system proposes 1.276,00 for each of these lines.

After that for the second line the amount becames 1.035,00

Don't understand why it happens

Thanks

Best regards