Chevrolet: electrical problem, distribution block, electrical problem

Question
i have the wiring harness all hooked up in the engine compartment.its getting power to distribution block,the horn,headlights.but not to the alternator or anything else.what could it be?

Answer
Andy;
  Hi - do you have a fuseable link on it. check it , and have you checked all of the fuses. take a test lamp and start at the battery and the large red wire in the harness and see where the juice gets lost at.and is the starter all hooked up - the power wire to it..