FM BAPI_ISUACCOUNT_GETDETAIL

Dear all, We are using FM BAPI_ISUACCOUNT_GETDETAIL. We need to post a document with a tax line and it is supposed that the FM has to create the line automatically. Does anybody have experience with this BAPI? We can post only documents with-out a tax line. We are mapping fields TAX_BASE_LOC_CURR, TAX_BASE, TAX_TRANSACT_KEY (= u2018MWSu2019), TAX_PERCENT_RATE (= 19), TAX_CODE, OTHER_TAX_CODE of the GENLEDGERPOSITIONS table. This is not enough. Seems that we need to do something more. Do we have to create a new line for the tax information? Thanks in advance. Fernando.