Oh dear, I guess you have cracked the two caesar cryptos...
This one is more difficult. Although a simple substitution is easily cracked...
Again the characters are limited to A-Z... But I think I can come up with a 256 version again.

Enjoy!

RW BKE IXZADKBW DOL WOM JIH PEIL BKAG ZW YPAEHL A IZ AZVPEGGEL NEPW UEXX LOHE WOMP GOXMBAOH SEW AG HPPIPDRRPORK BKAG XABBXE JKIXXEHDE UIG HOB BOO KIPL UIG AB