I’m using this plugin with version 3.4.2. and it works perfectly.
Your problem may be the result of one the following reasons:
1) A specific setting you’ve configured in NextGen Gallery.
2) A conflicting plugin.
My advice is to debug on a fresh test installation of WordPress i.e. a test server or subdirectory or a local installation using something like XAMPP.
Install the NextGen Gallery plugin and leave it at its default settings.
Next, install this plugin.
Once you’ve confirmed that all is in working order, begin progressively applying the configuration changes to match the website you’re currently working on. After that, begin installing whatever additional plugins you currently have.
This is basic debugging but it will solve your problem. The idea is to discover the point at which the plugin conflicts/breaks and lo and behold, you’ll arrive at the root and thereby the solution of your issue at hand.
When you do, be sure to post back and share the knowledge.