Sounds like you're doing it right, Liz, clicking the thanx icon in their post - have you tried reloading the page to see if your thanx appears at the bottom of the post - your browser may not be set to bring up the page afresh every time you visit it, so if you're just clicking the "go back" icon, you'll see the page as it was before you clicked the button...you can change your browser options to reload the page fresh every time, if you want..
all the best