Sorry to hear that you're having this problem! When you say it "won't post," is there a particular error message or other behavior that you're seeing? Or do you click "post" and then nothing happens? Also, are you posting straight through: http://www.getsatisfaction.com/walmart or are you posting from Walmart's Facebook page? Lastly, what browser are you using? I apologize for all the questions, but I'm just trying to gather as much information as I can so that our team can look into what might be causing this.
Again, sorry for the frustration! I look forward to figuring this out.