trailblazer no start just clicking at starter
 

i have a trailblazer that will not start. so let go to the being of the problem. the car was driven to gas station owner came out would not start acted like starter was bad . i replace the starter and it work no problem i thought. a week later had same problem no start just clicking at the starter not the relay. i thought i had gotten a bad starter so i changed it again but new starter did the same thing. so i pulled it out and bench tested it and it worked fine. then i put it back in hook up the wires with the starter off the block same thing just clicking at the starter. i check voltage at the starter all good check relay good jump relay same thing clicking. thought could be battery put a new one i had in same thing clicking. i have done every test i can think of to do and they all come out good anyone have any idea what i am missing