Error on EL Capitan Installation This copy of the Install OS X El Capitan application can't be verified. It may have been corrupted or tampered

I have created bootable pendrive using https://support.apple.com/en-in/HT201372 I am trying to dump ELCapitan on my mac. but it throwing error > This copy of the Install OS X El Capitan application can't be > verified. It may have been corrupted or tampered with during > downloading What i tried : **Setting date in terminal "date 0202020216", date 0101010116, ntpdate -u time.apple.com all didnot works.** P.S. 1) my ELCapitan .dmg is correct & downloaded from official Apple site. 2) hdiutil verify /Applications/Install\ OS\ X\ El\ Capitan.app/Contents/SharedSupport/InstallESD.dmg shows verified OS.