salix kde installation disc 64bit , can't boot

[indo7788]

I have downloaded kde installation disc 64 bit , i have md5sum it and it say correct file. After using unetbootin to put it in my usb , it can't use it to boot my pc from usb ,(motherboard already taught to boot from usb, and my usb listed correctly) it said
' missing operating system
operating system not found'
this thing had'nt happen with salix lxde installation disc. Is there any fix i can do ?
thank you
edited (using dd command to usb still have the same trouble)

[gapan]

Do you have a 64bit CPU?

[indo7788]

Do you have a 64bit CPU?

, yes , i use 64 bit computer , just like i said earlier , this thing isnt happen with lxde 64 bit installation disc edition .

[gapan]

So it must be a broken download or maybe your usb stick is faulty. There is absolutely nothing different between the lxde and kde installation files. There are some cases (extremely rarely) that md5 matches but the file has errors.