For some time I have noticed that when I am seeding, Tixati only establish a successful connection with a minority of available leeches.
Example is a (private tracker) torrent that Tixati currenrtly report as having 27 leeches. Out of these 27 I am only connected to 1, and connection timed out for the remaining 26. On another torrent from a public tracker I have 40 available leeches but get connection timed out on all of them.
Setting bandwidth limits well within my available bandwidth do not make a difference. For testing purposes I completely disabled the router firewall temporarily without experiencing any change in connection with leeches.

OpenSuse 13.1
Tixati 1.96

There are a ton of possibilities for that. First is the users are not on line. Click the tracker tab and see what it says. Another choice is the leeches are satisfied with their connections, i.e. have reached their max connections and ignore you.