challenge question: voucher number is already used as of date

Hello All,

Greetings,

its a challenge questions to all experts.

i have raise PO of 100 quantity and made GRN of 100 quantity, but i want to make 2 invoice like 50 qty of invoice separately and 50 qty of invoice separately.

when i post 2nd invoice then it error pop up :VOUCHER NUMBER:"########" IS ALREADY USED AS OF DATE "##-##-##" 

WORKING:

i have already changed sequences of invoice voucher in AP parameter. but i'm not able to post it. and that voucher number is not in use or not in conflict with other voucher series. 

Experts, waiting for your response to accept my challenge question.

Best Regards.