Why I can't use my voucher code for retaking CSA exam?

[MUCUILING]

I modified my certification language form japanese to english in the past.
At that time, my Voucher Code was reissued.
Now I want to make an appointment for a onsite test on www.webassessor.com,
but it reminds me that the Voucher Code cannot be used.
I want to confirm what happened.

My nowlearning ID:Cuiling.Mu.bp@jp.nttdata.com
My webassessor ID:Cuiling.Mu.bp@jp.nttdata.com

error:
Exam is a retake attempt or you were previously certified. A voucher can not be applied. You must pay the fee or submit a case to ServiceNow.

I haven't taken this exam in the past, and I haven't used my Voucher Code once.
the Voucher Code is Assigned status,so i think i can use it.
but now it cannot be work.
can you help me to solve this problem ?

thanks

[Dr Atul G- LNG]

Hi @MUCUILING 

Greetings!!

Please raise a case in Now learning and mention the above description to get it clarified.