Problem with payment and check

Question

HI
  My problem is the following; there were a invoce that arrived and it was paid 50% in advanced.
According to the invoice, it is supposed that in the Project Builder the complete quantity loaded to each project should be entered, and to the CIP.xxxx is loaded 50% that had been paid. That value in negative sign, to be able to cancel and to compense it. When one tries to enter this quantity in negative, the system show the following message: " only allowed numbers in positive." If we not carried out the before mentioned the check will come out for 100% of its value including 50% that was already paid.  
I need to know how to do the following: 
The check comes out for 50% that is the amount we have to pay and at the same time to enter in Project Builder the total that goes loaded to each project. 
Thanks in advance for your help
Message was edited by:
        Christian Meier
Message was edited by:
        Christian Meier

Answer 1

I want to clarify the transaction as under:
1] The reciept of goods [100 % value that you book to the project] is one thing; 2] the payment to the vendor [ 50%] is another.
Going by the above ,
You can treat the 50% Advance payment as 'down payment" [ Spl.GL Transactions].Use t/ code: F-48.
Once the material in entiriety is supplied you can regularize this down payment[T.code:FBA8].
For the supply made,you can book the entire 100% in the system.
Hope this clarifies your doubt.