Sorry that Rank Tracker isn't working for you. While at times it works perfectly fine, it does have a problem retrieving rankings sometimes. Because of this, we're going to be completely deprecating Rank tracker from the site in the next few months.
Basically, we're looking to add its best capabilities into our campaign-based rank tracking, and eventually provide you with an integrated tool with everything you need. Rest assured, we'll give you fair warning before we make significant changes.If you haven't tried it lately, check out the campaign-based rank tracking tool. It's got a lot of great stuff:
-Deep historical charts
-Google Analytics traffic correlation
-SERP analysis
-Global matching to automatically find the URLs that rank for your keyword in your campaign
-Auto rank tracking for up to 3 engines
-Competitor rank tracking-Both .csv and .pdf exports
Here's a guide that provides a great overview of the new rankings report capabilities: http://seomoz.zendesk.com/entries/20032346-rankings-report.
Also let us know if you rely on Rank Tracker but can't get what you need from the Web App instead: http://www.surveymonkey.com/s/5CKWL2F. Your input ensures that SEOmoz tools continue to meet your needs in the future, so thanks for sharing!
I hope you're able to get rankings at some point via one of these tools...