So i have Ubuntu installed in my system. I formatted the 8GB usb stick (mbr partition) created a FAT32 partition and copied contents of ISO.
After sometime i notice error in copying because install.wim is greater than 4 gb, Then too i booted from USB. The installer was working but it gave me(shoud give) an error.
So i formatted the drive again changed the filesystem to NTFS and now it is not booting.
To check that bootable USB is working correctly I booted it in my other system and it worked properly.
But not working in my current system(Lenovo yoga 500).