Chances are they are offline. Unfortunately, people's shares remain in the general hash search domain for some time even if they have logged off or crashed from using their particular gnutella program client. But then, there are also some who either (a) have upload slots set to zero, or (b) remove their shares as they download them (but their shares are still added to the shared files search domain for a period of time.)

Of course other reasons such as the uploader's upload slots are all busy & you are unable to get a download slot after a period of time. Sometimes due to them only having one or two upload slots open which means attempted downloads from them die easily & quickly slip into 'Need More Resources, or 'Stalled'.

Much advice on this topic .. even though some of it now a little old, has been given in this forum section: Download/Upload Problems

Basic issue is, people come & go from the network continuously. So the shares change. Searching, then 4-5 mins later using the 'Get/Find More Results' tool frequently helps here. Also, (1) the longer you are connected to the network, the better your search results should be, & (2) the more files you share, especially if they are related to the kinds of files you are seeking, then the better your search results should be. Have a good decent upload bandwidth setting, sharing lots of files, have at least several upload slots open, then search results will improve notably. Hopefully you will notice this with testing.

For those who do not wish to give much in the way of sharing either number of files, or upload slots or upload bandwidth, their search results tend to be somewhat limited & closed just as their minds are.

(Edit: forgot to mention: When you choose a file to download, it needs to first download the Hash of the file. Without this, the file will not download. So if LPE is unable to at least download the hash of the file first, it will highly unlikely ever start to download during that or later sessions even if you come across same/identical files in search results in later sessions. LPE only shows hash being downloaded by others in the upload window, not for your downloads in the download window unfortunately. So you never know if your attempted downloads have downloaded the hash or not (unless the file has started to download at some point.))