[Plugin: Next-Gen Gallery] Image Browser not working

I just installed and configured NextGen Gallery on my blog to use it in the Image Browser mode. here’s it “working” on a test post:

https://gomademascar.net/2007/12/03/hello-world/

[stay cool, that’s not a person, it’s a prop alien model from the Green Lantern movie]

so, when you click ‘next’ you’re taken to the same page, same image that opens the gallery. anybody may know what did i do wrong?

when I ticked the ‘image browser’ box i only hit ‘update’ on the WordPress’ permalink configuration – I never toyed with the htaccess file in the server.

any light on what i should do would be much appreciated.

thanks