Negative values in Service Entry Sheet

Question

Hi,
I am in need of creating service entry sheet lines with negative values (for a certain account assignment).
Bare with me, this will be long (-;
In my business scenario, (PS module, Construction Business) I use PO`s for external services with limits only. This PO has only one line ; the vendors are contractors who build for my company various types of buildings.
Every month I get an invoice from the vendor (contractor) for his monthly work, with a total sum, divided into various types of construction activities (Electricity, Sanitation, Paving and so on).
Against this invoice, a service entry sheet is created, with service lines from a service model containing construction works, in which I use material groups with account determination, so that each activity has its own GL account and cost element.
Immediately upon creation of the service entry sheet, logistic invoice verification is made (MIRO) based on the SES, and the payment is transferred to the vendor`s account.
My problem begins (ah! at last...) with the second monthly invoice and on.
It is almost by default that in this invoice, some of the construction activities from the previous month appear with negative values - mostly corrections.
Is there any way I can enter these negative values in a service entry sheet???
Remember - I cannot revoke the previous entry sheet (because of MIRO and payment)
I have already encountered error SE397, and the problem is that although the total value is positive, my negative values appear for independent account assignment lines.
Thanx in Advance,
Eytan.

Answer 1

Hi Sanjeev,
Thank you for your prompt reply.
I do not need to enter an entirely negative SES.
As I wrote, only one line is supposed to have a negative value, while the whole document is positive.
I was able to create a SES with negative values in lines, but only when I used the same material group (hence account assignment). Unfortunately, this does not always help me because In some cases, the negative value belongs to a single account assignment line.
And why can`t I have a similar (automatic) function like material movement 102?
SES automatically creates in the background GR document with material movement 101.
Eytan.