iPhoto '11 and cmd+k

I have some unused Keywords that I wanted to delete from iPhoto. Googling told me to use <cmd>+<k>, then click on [Edit Keywords].

However, <cmd>+<k> is rather unreliable in iPhoto '11 (Version 9.4.3 (720.91)). Sometimes it will bring up the keywords window and sometimes it won't, and I haven't been able to work out why.

Can anyone tell me a reliable way to open the 'Manage My Keywords' window in iPhoto, please?

Thanks.