Wont crank

We dropped the tansmission to replace a seal. The teuck
was running fine before this. After putting everything back
in the truck wont crank. We have tested the starter,
solenoid, ignition switch, and nuetral switch. All are good.
The only thing that we find not hot is the little wire
(actuater wire) coming from the starter to the fuse box.
We can run a wire from the hot post on the battery to the
starter and it starts and runs. ideas on what could be the
problem.