Mary from Mousesavers requests that the link not be posted publicly, so I don't think anyone can help you troubleshoot it that easily. But I just went in my 5/15 newsletter and the link that says "buy your tickets now through this private link" worked just fine for me.
What does happen when you go to the link? The very first thing at the top says buy now before prices go up, or something like that.
If you're not seeing that, I'm thinking it's an issue with your computer or something. You may just need to clear out your cookies and history from your browser.