I just installed Reload Tab on Double-Click and thought of the same thing. I promptly uninstalled that and then tried Reload Plus again but it didn't work.
Should I try uninstalling them both and just reinstall Reload Plus to see if it will work?
Could it also be something to do with my Logitech Keyboard "Setpoint" software? What should I define the middle-button as because setting it as "the middle button" doesn't make it work.