I would like to vote for migration a question to Super User StackExchange site but I can't.
When I try to flag the question, I choose It doesn't belong here, or it's duplicate.... After I choose Off Topic because... and now, I don't want to vote for migration to StackOverflow, thus I choose This question belongs on another site in the Stack Exchange network.
After these choices, I don't have opportunity to vote for migration to Super User. I only have choice for Webmasters Meta, ServerFault, StackOverflow or WordPress and if I don't choose one of these possibilities, I can't flag the question correctly. Here's a screenshot of the final step:
How can I vote for migration a question to Super User?
Is it a bug (I use Google Chrome as web browser)?
Maybe I need more reputation points?