Not all my posts showing up when searched

I have noticed that if I simply do a search for my username at the top most section of the forums there are several threads that do not show up including this one http://www.ipadforums.net/ipad-2-forum/69688-ipad2-search-broken.html . If I search using the advanced search and use Username field to do the search the missing posts show up. Why is that? Also do not see how one could even search via the iPad app for the forums here.