Withholding tax is not calculating...

Hi Experts,

I have configured all necessary setting for withholding tax posting,

but when i'm trying to post vendor invoice using f-43, withholding tax is not calculating.

accounting entry should posted like

purchase a/c....................Dr

to vendor a/c....................Cr

to withholding tax a/c.......Cr

but in my case is is posted like

purchase a/c...........Dr

to vendor a/c.........Cr

Please advice

Thanks

Manoj