Tax condition not appearing in sales order

Hi Experts,

when creating sales order for USA country, tax condition not getting updated for one customer 1234 alone.

Apart from this customer, every one getting tax value in sales order.

I have checked in some of the thread, and followed the instruction to check FTXP, OBBG and OX10 All are fine.

When i create sales order i receive the message "

Tax key not allowed. See table T007A" i have checked that table tax procedure TAXUSX have particular tax code.

checked in material master, cuatomer master and condition record, every thing assigned.

Main problem is except this customer 1234, remaining working fine.

Is there any place i need to check for this tax ?

waiting for your quick and valuble responce.

Thanks,

Karthikeyan R