PIA 2.8 on Cacti 0.8.7g

[lambchopper]

I just upgraded to Cacti 0.8.7g and then installed PIA 2.8 on a Ubuntu 9.04 server.

I had problems getting PIA to work. I kept getting an error:

Warning: array_merge() [function.array-merge]: Argument #1 is not an array in /usr/share/cacti/site/include/plugins.php on line 31

after following the instructions found here: http://cactiusers.org/wiki/PluginArchitectureInstall

In the end I fixed that by adding the following lines to my plugins.php file:
$plugins = array();
$plugins[] = 'mactrack';

Also, I do know that those lines should be in the global.php file, but when I put them there it didn't fix the problem.

After doing that and copying the mactrack folder in to my plugins directory I get a "mactrack" tab on the Settings page, but that's it. I also don't have the "Plugins Management" pages. So I think PIA isn't installed quite right.

I checked permissions and all file permissions seem to be correct.

Any help?