Also check the sqlnet.ora file under $TNS_ADMIN for NAMES.DIRECTORY_PATH = (TNSNAMES, EZCONNECT). If TNSNAMES is not there, then that could cause ORA-12154 too. For the sake of simplicity/consistency, keep the TNS Alias same as the Oracle SERVICE_NAME in the tnsnames.ora, like so:
WAAEDB =
(DESCRIPTION =
(ADDRESS = (PROTOCOL = TCP)(HOST = oracledbhost)(PORT = 1521))
(CONNECT_DATA =
(SERVER = DEDICATED)
(SERVICE_NAME = WAAEDB)
)
)