Due to a bug in the Invision software, multi-choice polls sometimes fail to work. After attempting to vote, you may see this (misleading) message:

Board Message
Sorry, an error occurred. If you are unsure on how to use a feature, or don't know why you got this error message, try looking through the help files for more information.

The error returned was:

You did not choose a poll choice to vote against. Please go back and ensure you click on one of the radio buttons next to the choice you wish to vote for.

Although you may be unable to vote for a particular combination of options, other combinations may work fine, so it's worth trying again.

There's nothing we can do about this glitch, unfortunately, but it's worth knowing that one-choice polls always work.