Some accounts, especially newbies, have restrictions, but I believe that your rank will enable you to search with out that error. I have now tried to click on the search button several times and have not encountered a problem.
Nope, I don't think it has anything to do with rank because I also experience it from time to time. However, reading what user Cantsay said; I guess that's the likely cause.
I think I will start making use of that now. I used to think it was mainly for archiving posts.