wp-polls: cannot edit or add polls

I’ve installed the wp-polls but although it worked once, now I cannot add/edit any polls – on trying to add a new poll, or edit the default poll, I get a “You do not have sufficient permissions to access this page” message.

I have checked:
[1] My admin level privileges (this error message is only prompted by edits to THIS plugin).

[2] Updated WordPress to latest version.

[3] Uninstalled, deleted files and reinstalled plugin. Twice.

[4] Logged out, logged in again.

[5] Cleared browser cache, closed browser, then [4].

[6] Tried from different browser where I hadn’t logged in before.

[7] Created new admin level user/login, same problem.

Any help greatly appreciated.

http://ww.wp.xz.cn/extend/plugins/wp-polls/