How to generate unique sequence numbers on the payment document?

  While processing the payments for the suppliers, the same sequence number 'A' is showing up in the request header for all the payment  eft files generated.The logic in the column position 34 in the eft document  decodes the sequence number to 'A' in all the files. 

Expected: The sequence number should be 'A', 'B', 'C'... in the consecutive eft files. 

Please help what I am missing here. 

- thank you/ 

Current setup for the eft document: 

Sequences:

 Hint: Define sequence generators…

<DEFINE SEQUENCE> PaymentsSeq

<RESET AT LEVEL> OutboundPaymentInstruction

<INCREMENT BASIS> LEVEL

<START AT> 1

<END DEFINE SEQUENCE > PaymentsSeq

  

<DEFINE SEQUENCE> US_NACHA_CCD_DAILY_SEQ