Connect hp 1730 ext monitor

The HP 1730 is connected and powered up. When powered up, monitor goes to Sleep right away. System Preferences > Display brings two windows, HP 1730 and Built In Display. Selecting "Optimize For hp 1730" in either window shrinks computer display; selecting "Optimize for Built-in Display" on either window brings normal display on computer. Changing the Optimize For in either window changes the Optimize For in the other window to the same thing. Thank you