Editing a Poll

[Sinitrena]

I have a poll running in the Fortnightly Writing Competition at the moment.

Someone asked me to extend the poll for a bit. I tried to edit it, and I do have the option to change the days it is supposed to be running:


Showing how the edit screen looks for me at the moment. Original number when posting the poll was 4. I can type a different number.
Clicking on save doesn't add any days to the poll though, it seems. (I also tried to shorten the deadline right after I created the poll, which also didn't work, but I figured it made sense not to allow this)

I have never used polls before, so I'm not sure if I should be able to change this and it just doesn't save it for some reason or if the option shouldn't be there in the first place.

I have not tried to change anything else in the poll, as I obviously want it to run and I want a fair result, so I don't want to play with it and accidentaly change something that changes the results.

Any idea what went wrong here?

[AGA]

When do you actually want it to end?

[Sinitrena]

Two days more would be nice.