Tax is Not Calculated for Expense Report Invoices when assign new OU to employee

Hi,

Before employee supplier A was assiged to Operating Unit X. Now this supplier is assigned to Operating Unit Y. But at the new Operating Unit, the Tax is not calculated for Expense Report Invoices of supplier A. This issue doesn't happen with other employee supplier. I've checked tax setup & supplier information but not found the cause. Pls help me solve this problem.

Thanks,

Dat