no crank from key

Car won't crank from key not in park and not in neutral. New ignition switch last year, new starter relay. I've checked and double checked nss and the connection is tight. Turns over fine when I jump the relay. Also when I,hit the key the whole,car goes dead. Till I let off start position. Any direction would be appreciated

Check the body ground. The skinny wire coming off the negative side of the battery.