1) You are asked by the forum rules to add the URL of your page so we can check your problem
2) you did not tell where you expect to see the title which is defined by the plugin. It is shown in the title bar of browser, not as blog title in the header of the page
3) I activated AllinOneSEOPack, defined a title and the title showe up in the title bar of the browser. There is no problem with that.
Check whether you disabled Suffusion's SEO functionality in Blog Features / SEO / Meta Settings
That might be what you forgot to do.
And the Mantra again: Clear your browser's chache, test with more than one browser!
Good luck, Connie