Tape does not expire after 2 weeks

Hi Guys,

I have looked all forums and tried registry fix to expire 

HKLM\Software\Microsoft\Data protection manager\Media manage\ExpiryDatesetondaystart and set the value to 1.

I have got two sets of tapes Monday to Friday being used for long term protection, retention period is one month.

1 recovery point every one day for the last 2 weeks.

When I rotate the second week tape it does not expire or free up. when there is no space available it fails the job.

Any idea in detail would be appreciated.

Thanks