Normally the error FZ003 appears if you create a payment proposal
for some payment ID, date; then leave it as is; then create another
payment ID, date and execute payment proposal generation. Vendors/
customers are blocked in the first payment proposal.so pls.check whether you have several other proposals which are outstanding. if yes, then you
could delete these payment proposals or execute the payment runs to
the end. This action will allow to execute subsequent payment runs as
company code will be unblocked for the subsequent payment runs by
the system. Don't forget to delete unsuccessful payment proposals
(with error FZ003) and run proposal generation again.
Addition, if you selected the payment method C in free selection tab, the
field name is LFB1-ZWELS , not BSEG-ZLSCH.
Please also check the due date of the posted invoices of the vendor,
the payment run parameters especially the fields 'docs entered up
to' and 'customer items due by' fields.