Also with LW 5, you may need to (1) enable the sharing of documents .. found in first window of options. (2) go to Tools -> Options -> Advanced -> Files, and click on the File Extensions management button. Make sure file types like pdf, LIT, etc. are checked under the Documents section.

LW LW 4, Tools -> Options -> Sharing -> Types. Make sure the file types you wish to share are both listed & checked. By default, .lit & .doc & .rtf are not checked for LW 4 AFAIK but I might be wrong.

Something else to keep in mind is, if you keep continually searching the same search terms over & over, your ultrapeers 'might' start blocking the searches. This may take some days to recover from.