Oracle Database Discussions

RMAN do not delete old archivelogs after taking archive backup .Issued command
RMAN> BACKUP ARCHIVELOG ALL DELETE INPUT;
it only deletes few old archivelogs....... but still many old archive logs are there

.................i think database might haved switched from archivelog to noarchivelog then again archivelog mode.I don't think there is any retention for archivelogs once backup is taken.
Please refer any other ideas .
Also please refer oracle view to see database archive mode history. v$database only shows current archive mode
.................THanks in advance :)