Revote after editing a poll

[MajidOnline]

hi
Suppose that I have a thread with a poll a few users have voted, after a while I edit the poll by setting number of voted to zero and changing options.
now I've edited and made a new poll in the thread and problem here is that the users voted before editing process can't vote anymore. I mean I've changed the votes to zero in each option but it seems they've still voted the poll and can't participate in the new one.

how can I do sth so each time I edit poll all the users can vote again even if they've voted before?
thx for your time