I have a 1999 plymouth grand voyager it wont start or turn over?

it wont even click when i turn over the ignition i checked the fuses, relays and the starter it all works fine acept for one of the wires that plug into the starter which i think is the ignition wire i was testing to se if i would get any juice by hooking up a tester from the main battery wire that hooks up to the starter and from there to the ignition wire tha hooks up to the starter also but there is no juice how do i fix that problem? do i follow the harness all the way along to see for damaged eires or do i get a new harness