Your not Alone.
Just tested another Tool Bar Ad-ons for alexa Raking and seems not working at all.
I Don' Know why But my Current Alexa Rank Ad-ons Sparky is not working and then i just install Search Status but its also not working.
Maybe its on Alexa's side. Maybe they Change some of there Techy codes in Ranking. I Don't Know, lets just W8 when it's Fixed.
Just Letting you know your not alone :D