So I came across this issue when I installed a recent application (Packet Tracer7.0 [CISCO]). When I run it trew the sh file on it's folder it works properly well and shows the respective icon on the dock. So far so good, but when I go to my slingshot I found it curious that no icon (or desktop entry) was added there and because of this I believe I can't do the action "Add to dock". More interesting was going on to the /usr/share/application folder and finding that many desktop entries not only for this especific app are there but don't show up in the slingshot menu. Any sugestions?
[Desktop Entry]
Exec=PacketTracer7
Icon=pt7
Type=Application
Terminal=false
Name=Packet Tracer 7.0