SQLScript error in AMDP

Hello,

please guide me with below error,

  METHOD TEST_CEFUNC BY DATABASE PROCEDURE

                         FOR HDB

                         LANGUAGE SQLSCRIPT

                         options READ-ONLY

                         USING VBAK VBAP.

LT_VBAK = CE_COLUMN_TABLE("VBAK");

LT_VBAP = CE_COLUMN_TABLE("VBAP");

ET__DATA = CE_JOIN (:LT_VBAK,:LT_VBAP,["VBELN"],["VBELN","AUGRU","NETWR","BSTNK","KUNNR","POSNR","MATNR","KWMENG"]);

ENDMETHOD.

SQLSCRIPT message: Parameter must be a valid column table name: ZCL_TEST_1=>VBAK#covw  

Why am i getting above SQLScript error? I am using HANA database system and VBAK/VBAP are column based tables.