I have created all the Withholding Tax Codes as follows
Administration
>Setup
>Financials
>Tax
>Withholding Tax
and has mentioned Withholding Tac code, Name, Category(Invoice), Rate, Base Amt, Official Code, and Account.
When I was trying to create A/R Invoice
Sales-A/R--> A/R Invoice
At withholding tax column I has selected Yes. A withholding tax Table has been generated at the Code column I pressed the tab to select the Withholding tax code a screen appeared as List of Withholding Tax in the screen I found there are no withholding taxes present. Approximately I created 60 codes for withholding taxes where it can be visible. I have Defined the Effective date and Rate from Tax Definition