transaction log for 'database' is full due to 'LOG_BACKUP'.

I am getting this error when trying to access my application.

I can see that my .LDF file is HUGE and I thought I combated this when I set the recovery model to FULL and then performed daily full backups and 30 minute t-log backups - as I thought this would shrink the LDF file, but evidently it has not.

I'm stuck for ideas on what to do.