Hey John. Thanks. I discovered that if you type in the "Update" box the hashtag - it will take. If you copy + paste a sentence from another place (like word, or Facebook or something) the copy and paste does not let Yammer recognize the hashtag as a tag. It just thinks it's regular text. I was using Google Chrome too. Good to know for the future. If I want the hashtag to work, I have to physically type it in Yammer, not copy and paste from somewhere else.