Trying to boot up on Mavericks USB Install Drive, receive prohibited sign on screen
I've had mixed success using that bootmaker utility.  Try Apple's instruction here

https://support.apple.com/en-us/HT201372

Assuming a) the 'install osx mavericks' file is in the Applications folder and b) your USB drive is named MyVolume, open Terminal and run this command. 

sudo /Applications/Install\ OS\ X\ Mavericks.app/Contents/Resources/createinstallmedia --volume /Volumes/MyVolume --applicationpath /Applications/Install\ OS\ X\ Mavericks.app