Works fine for me when I enter your username. Without wanting to sound patronising, I assume you’ve selected the right forums, ‘search by’ dates and so on?
Could you have left it with the defaults (About This Message Board and Since 5 Days Ago)? If so, that explains it, because when I search for your username using the defaults, it only brings up this thread, but if I change it to (choosing randomly) MPSIMS and Since 30 Days Ago, I get four threads.