VAT number Thailand skip

Hi,

I am configuring VAT input tax for country thailand in ECC 6.0 release.

The official VAT input number is generated correctly on document header text.

But the number is always skip by 1 number when i do a posting via FI (eg vendor invoice, document type KR)

Example:

firt document posted is with tax number 90000, then when i post another document, the number was jumped to 90002

Kindly your input on this issue.

Thanks for your help.

Rgds,

Henny