Table schema:
CREATE TABLE table_name_51 (copa_mercosur_1999 VARCHAR, team VARCHAR, copa_libertadores_1999 VARCHAR, copa_conmebol_1999 VARCHAR)

Question: What is the copa mercosur 1999 result for team grêmio, who did not qualify for the Copa Libertadores 1999 and Copa Conmebol 1999?
SQL: SELECT copa_mercosur_1999 FROM table_name_51 WHERE copa_libertadores_1999 = "did not qualify" AND copa_conmebol_1999 = "did not qualify" AND team = "grêmio"