I can´t run the install app in a new blank HD

Hi, i just follow all the steps to create a bootable flash device with El Capitan OS X, but when it starts running, appears a message with: This copy of the install OS X El Capitan application can`t be verified. It may have been corrupted or tampered with during downloading.

i've tried this for 5 times and it appears the same.

Please help me how to proceed in a new SSD for my MacBook Pro 2011