Finding enhancement point for transaction XD01 "warning message"

In the transaction XD02 if user enters wrong Tax Jurisdictn code we want warming message but currently message is coming right but its coming as error message.

We need to change the following method but in this method there are sevral note are implemented.

Class name : CL_TAX_TXJCD_DETERMIN_SHELL

Method : CHECK_TXJCD_EXTERNAL

help with enhancemengt point (implicite or user exit ) so i can can this message into error.