XF 1.5 Search, changed to "3 characters" -> no results

Hi there,

I just changed my minimum length of the search items from default 4 to 3. After that I searched for a 3-letter word wich definately is in the forum and I got no results from the search.
After that I rebuild the search index, which didn't help.

What can I do? Did I miss another option?

Thank you for your help!
Hi Mike and thank you for your reply.
My forum is being hosted at a website hoster - no full server access :( but I tried the support there and we'll see if they can do anything to change this setting.