Help w/ speedo cable

[Daffy]

i recently bought a new speedo cable for my 05' 800 classic. Installed it and tightened the screw on the back wheel and to the speedometer, 115 miles later it came out. I seriously need help to figure out how I alleviate this problem. What am I doing wrong or what my bike isn't responding to?

Thanks in advance
Daffy

[Ice Cube]

Threads may be a little worn. Try cleaning up the screw and housing threads and use blue locktite.