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!

JV UTA FPGKBTUV BCD VCR XFO MAFD UTKW GV IMKAOD K FG KGLMAWWAD YAMV HAPP DCOA VCRM WCPRUKCO EAV KW OMMFMBJJMCJT UTKW PKUUPA XTFPPAOBA HFW OCU UCC TFMD HFW KU