comment deletion does not work

Hi, I installed vote up/down module as the install.txt says.

It works fine but I found that automatic comment deletion does not work.

After installing every necessary modules (voting api, vote action, actions...etc), I configured the vote action with the following options.

action: unpublish comment
condition: the total sum of vote is less than -5

Do you have any idea? I hope this is my mistake. :-)

Thanks very much.