Payment run F110- own z-field not transferred from invoice document

Hi,

we have the following situation:

We created a z-field which needs to be populated in all FI documents.

Now, when we enter a vendor invoice we have the field populated as required. However, when we run the payment program this value is not taken into the payment document. (Due to the validations we have there is even an error issued.)

How can I transfer the value from invoice document into payment document? Is there an exit or BTE for that or any other way?

Thanks

Hein