You may not be getting and search results because you're internet connection may be poor. Look in the bottom left-hand corner of the LimeWire screen to see how good of a connection you have.
Then again, the reason you may not be getting any results for that song is because no one has it in their LimeWire library so others can download it at the time you did your search. Also, try going into LimeWire at different times of the day. I find that sometimes my searches are better in the morning or late evening. If you try doing a search at different times through the day you might come across someone that has that song.