Hello, i have a problem with BootCamp

Hello people, i have a problem with BootCamp, im really sad...
Bootcamp assistant dont create the Bootable USB, it say, not been able to create the executable memory drive usb...
And then i cant do nothing but, close the assistant... sorry for my bad english, but time ago, i was able to install Windows and all that... i dont know why now i cant...

And i already did it in Mavericks, it just dont let me right know, and i tried to reinstall all OS X, and try again, but nothing... i still get the same error...Please help me :/

My system is in spanish... but you know what is this...